Limnological Survey of Lake Ontario, 1964

LIMNOLOGICAL SURVEY OF LAKE ONTARIO, 1964

GREAT LAKES FISHERY COMMISSION 1451 GREEN ROAD ANN ARBOR, MICHIGAN

APRIL, 1969 CONTENTS

Foreword...... iv Chemical Characteristics of Lake Ontario Herbert F. Allen...... 1 Planktonic Diatoms of Lake Ontario Jerry F. Reinwand ...... 19 Lake Ontario Phytoplankton, September 1964 Roann E. Ogawa . , ...... 27 The Benthic Macrofauna of Lake Ontario Jarl K. Hiltunen ...... 39 Fishery Survey of U.S. Waters of Lake Ontario LaRue Wells ...... 51 Appendix. Location of Stations on Lake Ontario. . . . 58 FOREWORD

The major weakness in our knowledge of the St. Lawrence Great Lakes has been the lack of detailed lakewide hydrographic surveys. The shortage of data from such surveys has made difficult the measurement of environmental changes and in turn has hindered our efforts to recognize, control, and prevent pollution. Studies are urgently needed to provide a base from which we can measure the rate at which the Great Lakes are changing. Due to an almost complete lack of data from Lake Ontario, the Bureau of Commercial Fisheries conducted a lakewide hydrographic and fishery survey of that lake in September 1964. Sam- ples were collected in the open waters; shallow inshore areas and areas that were obviously polluted were intentionally avoided. The Lake Ontario survey lasted 10 days and included the measurement of several chemical constituents of the water, identification and counts of phytoplankton, and the sampling of bottom fauna and fish populations. Other studies have been conducted on Lake Ontario since 1964 but very few were lakewide. The combination of isolated studies with lakewide surveys at periodic intervals should give a good base from which to measure changes that will undoubtedly con- tinue in Lake Ontario. As pollution abatement becomes a reality, we should be able to measure the rate of recovery of the lake to a more desirable condition. The five papers in this publication document the 1964 survey; each paper is complete within itself. Figure 1 of the first paper shows the locations of all stations at which samples were collected. The latitudes and longitudes are listed in the Appendix. The papers on plankton and bottom fauna each contain maps which show only the stations sampled for the particular study. The paper on fish populations describes the fishing locations in the text. CHEMICAL CHARACTERISTICS OF LAKE ONTARIO’

Herbert E. Allen U.S. Bureau of Commercial Fisheries Biological Laboratory Ann Arbor, Michigan

ABSTRACT

Records are presented of Na+, K+, Ca++, SiO,, pH, alkalinity, 0,, and specific conductance at 106 stations in Lake Ontario. These data are compared for east-west and surface-subsurface variations. Water quality in Lake Ontario is similar to that in Lake Erie with the exception of dissolved oxygen. The open waters of Lake Ontario had no areas of serious oxygen depletions.

Introduction

The chemical characteristics of Lake Ontario were studied from samples collected in the open water of the lake. Other investigators have used open-water samples to assess eutrophication in the Great Lakes; near-shore water may be influenced by local- ized pollution. The present report gives the results of chemical analyses of the water from samples collected in 1964 and compares the find- ings with earlier conditions in Lake Ontario. Previous chemical surveys of Lake Ontario have been reported by the International Joint Commission (1951), Rodgers (1962), Kramer (1962), the Great Lakes Institute (1965), and Dobson (1967). The Bureau of Com- mercial Fisheries also conducted a limited survey in 1961 (unpublished).

Methods

Nansen bottles were used to collect surface and subsurface water samples at 106 stations (Fig. 1). A bucket was used at

‘Contribution No. 366, Ann Arbor Biological Laboratory, U.S. Bureau of Commercial Fisheries. 1 Figure 1. Lake Ontario showing locations of all stations at which samples were collected. stations where only a surface sample was taken. Surface temperatures were measured with a recording thermograph and subsurface temperatures with reversing thermometers. Several water samples were obtained from near the bottom (without temperature measurements) with a horizontal sampler (Joeris, 1964). Analy- ses for alkalinity, pH, and dissolved oxygen were performed only on the samples collected in Nansen bottles. Bathythermograph casts were made at all stations. Samples were analyzed for alkalinity, pH, dissolved oxygen, and specific conductance aboard the Cisco and for Na+, K+, Ca++, and Si02 at the Biological Laboratory of the Bureau of Commer- cial Fisheries, Ann Arbor, Michigan. Sodium, potassium, and calcium were determined flame photometrically. Silica was measured colorimetrically as the heteropoly blue. After the pH de- termination a potentiometric titration was used to measure alkalinity. The Alsterberg modification of the Winkler method was used for oxygen measurements (American Public Health Associa- tion, 1965). Conductivity was measured at the ambient temperature and corrected to 18° C by correction factors given by Smith (1962).

Chemical Values and Their Variation

The horizontal variation in the chemical composition of open Lake Ontario was remarkably small (Table 1). The chemical sampling, however, was not designed to detect pollution, and inshore areas with occasional high concentrations of chemicals may not have been detected by this survey. Evidence of enrichment was found only near the mouth of the Oswego Rover. At stations 69 and 106, sodium concentrations were 34.0 and 20.7 ppm, calcium concentrations were 51.3 and 40.5 ppm, and conductivity values were 452 and 318 ,umhos respectively. The average values for all stations (Table 2) were 12.0 ppm sodium, 38.18 ppm calcium, and 277.0 ymhos. Enrichment was not detected off the Genesee River (stations 58 and 59) nor in the Toronto area (stations 16 and 17). Hiltunen (1969) reported that both of these areas showed evidence of enrichment on the basis of the numbers and species of bottom fauna. Average values and ranges for chemical and physical measurements of the water of Lake Ontario are presented in Table 2. Although the range of values for some constituents was large, most values were within much narrower ranges. For example, the range for sodium in all samples was 10.4 to 34.0 ppm, but in 96% of the samples the range was only 10.8 to 13.2 ppm (Table 3). High or low values may have been caused by errors in sampling or analysis, the influence of tributary streams, unusual biological activity, or equilibrium with bottom sediments. Table 1. Chemical and physical data for Lake Ontario, 1964 [For station location see Figure 1.]

Tempera- Dissolved Specific Bicarbonate Total Na+ Kt Ca++ SiOz ture conductance pH alkalinity alkalinity oxygen ppm ppm ppm (o C) (ppm) WI6 x lo? (ppm CaCO,) (ppm CaCO,) ( ) ( ) ( ) (IJprn) September 8 1 0700 0 19.4 **** 279 *** * *** 11.7 1.2 42.5 0.6 2 0730 0 20.6 **** 275 *** * *** 11.7 0.8 41.1 0.7 3 0750 0 18.3 **** 272 *** * *** 11.6 0.8 41.1 0.6 4 0759 0 18.6 8.6 279 8.1 0 100 11.4 1.0 41.7 0.6 11 17.8 9.0 279 8.3 0 102 11.8 1.2 41.3 0.6 13 16.6 9.2 274 8.0 0 100 11.0 1.4 37.7 0.7 5 0910 0 20.0 9.2 271 8.2 0 103 11.4 1.4 36.9 0.6 11 15.1 9.4 276 8.1 0 103 11.4 1.4 37.7 0.6 15 12.4 9.5 287 7.9 0 102 10.9 1.5 37.6 0.7 31 5.6 11.3 282 7.7 0 102 10.9 1.3 36.7 0.9 91 4.2 11.8 287 *** 0 103 11.2 1.3 42.6 1.6 6 1014 0 18.4 **** 269 *** * *** 11.9 1.4 38.7 0.5 7 1041 0 17.6 10.4 276 8.4 4 99 11.9 1.4 38.8 0.4 18 8.9 10.4 288 7.8 0 101 12.1 1.3 39.8 0.8 26 5.4 11.3 290 7.6 0 102 11.9 1.4 40.8 0.8 52 4.3 12.1 292 7.8 0 100 11.5 1.4 38.2 0.9 100 4.1 11.7 296 7.6 0 102 11.5 1.3 40.1 1.1 8 1200 0 19.0 10.4 280 8.4 6 101 11.9 1.3 37.3 0.6 12 15.8 9.4 277 8.1 0 99 11.7 1.3 40.1 0.7 18 9.7 10.1 291 7.7 0 102 11.5 1.3 38.7 0.8 30 5.3 10.2 286 7.8 0 101 10.9 1.4 38.2 1.2 91 4.4 11.3 285 7.7 0 102 11.3 1.3 38.8 1.5 9 1250 0 18.8 **** 271 *** * *** 12.1 1.4 38.2 0.7 10 1320 0 18.9 **** 272 *** * *** 12.0 1.2 35.7 0.7 11 1355 0 19.6 10.2 273 8.6 9 100 12.2 1.4 36.6 0.8 9 13.3 8.5 306 7.9 0 101 12.0 1.3 37.4 1.2 18 7.7 9.7 285 7.6 0 103 11.8 1.2 38.7 1.4 , 12 1455 0 19.5 **** 269 *** * *** 11.9 1.4 36.6 0.7 13 1525 0 18.6 **** 271 *** * *** 12.3 1.2 36.8 0.6 14 1555 0 17.3 10.4 277 8.4 4 99 12.2 1.3 35.5 0.8 9 17.7 10.4 278 8.2 * 97 12.9 1.3 37.4 0.8 12 10.2 9.8 284 7.8 * 102 12.9 1.2 39.6 1.0 29 6.6 9.2 290 7.6 * 103 11.6 1.3 43.3 1.3 15 1645 0 18.2 **** 272 *** * *** 12.3 1.2 40.6 0.7 16 1712 0 17.0 **** 274 *** * *** 12.1 1.3 40.0 0.8 September 9 17 0800 0 16.2 9.9 272 8.2 * 99 11.9 1.3 39.8 0.8 9 9.6 9.6 285 7.7 * 103 11.4 1.3 39.4 1.2 18 4.9 10.6 287 7.7 * 104 11.7 1.4 40.9 1.3 18 0853 0 18.0 10.0 273 8.6 4 97 12.0 1.3 39.7 0.7 11 16.8 9.3 274 8.2 0 99 11.7 1.4 39.8 0.8 18 5.6 11.2 287 7.7 0 102 11.6 1.4 38.2 1.0 91 4.2 11.9 289 7.9 0 102 11.4 1.5 39.9 1.4 19 1039 0 18.3 10.3 271 8.5 3 99 11.6 1.3 39.6 0.7 11 17.2 9.4 280 8.2 0 99 11.5 1.4 39.3 0.8 15 10.9 9.5 283 7.8 0 100 11.3 1.4 39.2 0.9 31 5.1 11.8 284 7.8 0 103 10.8 1.3 39.6 1.0 122 2.7 11.3 282 7.8 0 103 11.2 1.4 39.9 1.8 20 1134 0 18.2 * *** 270 *** * *** 11.1 1.3 40.0 0.7 21 1210 0 18.0 10.3 273 8.3 1 99 11.9 1.3 40.4 0.8 9 14.8 9.9 279 8.1 0 99 11.5 1.3 38.2 0.9 15 11.0 9.4 278 7.8 0 101 12.3 1.3 39.4 0.9 25 5.5 10.6 289 7.7 0 101 13.1 1.5 38.0 1.1 88 4.2 11.6 283 7.8 0 101 12.0 1.3 38.2 1.3 22 1253 0 18.2 **** 270 *** * *** 12.4 1.4 35.4 0.6 25 1320 0 18.3 9.7 269 8.5 4 97 12.6 1.5 34.8 0.7 12 17.6 9.1 274 8.3 1 99 12.0 1.4 35.4 0.7 18 8.8 9.6 283 7.8 0 100 11.1 1.3 39.1 0.9 46 8.1 11.3 283 7.7 0 102 11.1 1.2 38.6 0.9 91 4.2 11.7 285 7.8 0 102 11.1 1.2 38.4 1.1 23 1423 0 17.0 10.1 275 8.4 3 100 12.1 1.3 36.9 0.7 9 14.1 9.9 270 8.2 0 100 12.4 1.2 37.6 0.8 18 9.3 9.7 292 7.6 0 100 12.1 1.2 38.5 1.1 September 10 24 0755 0 18.2 **** 268 *** * *** 11.6 1.3 34.4 0.7 25 0819 0 18.4 **** 273 *** * *** 11.7 1.0 36.8 0.5 26 0948 0 18.4 **** 271 *** * *** 11.6 1.1 34.1 0.5 27 1018 0 18.3 **** 268 *** * *** 10.4 1.0 36.0 0.5 28 1040 0 18.6 9.8 271 8.4 3 96 11.8 1.1 35.3 0.6 12 18.1 10.2 268 8.4 2 97 11.2 1.1 36.3 0.6 15 9.1 10.8 278 7.4 0 97 10.6 1.0 38.6 0.7 30 5.2 11.3 298 7.4 0 100 10.5 1.2 38.4 0.8 90 4.2 12.0 296 7.8 0 103 11.0 1.3 39.3 0.8 Table 1 (Continued)

Date Tempera- Dissolved Time Depth Specific Bicarbonate Total and ture conductance pH alkalinity alkalinity Na' K' Ca++ SiOa (EST) (meters) oxygen ppm ppm station (o C) (ppm) (Km x lo? (ppm CaCO,) (ppm CaCOa) () () ww' ' uww' ' September 10 142 4.1 11.4 286 7.8 0 106 11.2 1.3 38.8 1.3 29 1158 0 19.1 **** 267 *** * *** 11.3 1.3 35.8 0.5 30 1225 0 19.4 9.7 217 8.6 6 102 11.4 1.3 37.2 0.6 7 19.3 9.3 280 *** * *** 11.4 1.2 37.0 0.6 15 13.4 9.2 284 *** * *** 12.1 1.2 38.7 0.8 23 11.3 9.8 283 *** * *** 11.6 1.2 38.0 0.9 30 7.2 10.4 281 *** * *** 11.2 1.1 38.0 1.1 38 ****I 11.0 279 *** * *** 11.2 1.2 37.7 1.0 45 5.1 11.0 280 *** * *** 10.8 1.2 39.6 1.2 53 3.4 11.4 283 7.9 0 106 11.4 1.4 40.4 1.2 61 4.4 11.6 281 7.9 0 107 11.0 1.3 42.0 1.4 68 4.2 11.2 281 7.9 0 107 11.4 1.3 40.5 1.4 76 4.1 11.4 285 8.0 0 107 11.4 1.3 39.6 1.4 83 4.2 11.3 285 7.9 0 108 11.2 1.3 40.0 1.5 31 1425 0 19.5 9.7 273 8.7 7 103 11.7 1.3 38.6 0.6 9 13.4 8.6 275 8.4 4 103 11.9 1.3 38.6 0.6 18 11.3 9.8 288 8.0 0 107 11.5 1.3 40.6 1.1 September 12 32 1021 0 18.1 9.0 272 8.6 3 103 11.4 1.3 37.9 0.6 10 18.5 8.9 272 8.2 0 100 11.0 1.2 38.0 0.6 18 12.1 9.4 281 7.9 0 104 10.9 1.3 39.2 0.9 33 1125 0 17.8 9.2 273 8.5 3 104 11.4 1.3 37.8 0.7 15 18.2 9.3 269 8.3 1 101 11.6 1.2 37.2 0.8 46 5.8 10.6 283 7.8 0 102 11.5 1.3 39.8 1.2 86 4.2 11.1 286 7.8 0 104 11.2 1.3 40.3 1.7 34 1235 0 17.4 **** 267 *** * *** 11.6 1.3 37.6 0.7 35 1345 0 17.7 9.4 264 8.4 3 101 12.2 1.5 37.4 0.6 15 17.7 9.0 272 8.3 1 100 11.5 1.3 38.1 0.6 30 7.6 10.1 277 7.2 0 101 11.1 1.4 37.5 0.8 91 4.2 12.0 284 7.6 0 102 11.9 1.5 39.5 0.8 179 3.9 11.4 281 7.5 0 102 11.6 1.4 39.2 1.4 36 1427 0 18.4 **** 257 *** * *** 11.9 1.4 36.3 0.5 37 1457 0 18.3 **** 261 *** * *** 11.6 1.4 36.2 0.6 September 12 38 1547 0 17.7 9.4 269 8.5 4 99 11.5 1.3 36.6 0.6 12 17.4 8.9 267 8.2 0 100 11.6 1.4 36.6 0.6 30 5.0 11.2 282 7.6 0 102 11.5 1.3 37.6 0.8 61 4.1 12.0 288 7.9 0 105 12.1 1.3 39.2 0.7 91 4.0 10.9 289 7.8 0 105 12.3 1.4 37.1 1.3 39 1658 0 17.2 **** 264 *** * *** 11.9 1.2 38.4 0.7 40 1740 0 16.0 9.6 271 8.2 0 101 11.8 1.2 39.6 0.7 9 16.0 9.5 275 7.8 0 97 12.1 1.1 38.8 0.7 18 13.9 8.9 279 7.7 0 102 11.6 1.1 38.6 0.8 September 13 41 0540 0 14.4 **** 289 *** * *** 11.3 1.1 38.8 0.9 42 0610 0 15.5 **** 282 *** * *** 11.3 1.1 41.2 0.8 43 0640 0 17.1 **** 278 *** * *** 11.6 1.1 38.1 0.7 44 0710 0 17.1 **** 274 *** * *** 12.0 1.1 39.0 0.6 45 0740 0 17.9 **** 271 *** * *** 11.7 1.2 37.2 0.7 20 17.4 **** 271 *** * *** 11.6 1.2 38.4 0.7 25 12.4 **** 274 *** * *** 11.5 1.3 38.6 0.8 38 7.9 **** 268 *** * *** 11.4 1.3 40.4 1.3 46 0900 0 17.0 **** 274 *** * *** 11.5 1.3 38.4 0.7 47 0930 0 17.5 **** 272 *** * *** 11.2 1.3 38.5 0.6 48 1000 0 ****' **** 271 *** * *** 11.4 1.4 36.8 0.6 49 1030 0 17.9 **** 269 *** * *** 11.2 1.4 38.0 0.6 50 1122 0 18.5 9.2 271 8.3 1 99 11.4 1.3 38.0 0.6 17 13.6 8.1 279 7.7 0 99 11.3 1.3 39.7 1.0 18 99.9 8.2 285 7.7 0 103 **** *** **** *** 51 1224 0 18.8 **** 268 *** * *** 11.2 1.3 36.2 0.6 52 1254 0 18.6 **** 275 *** * *** 12.3 1.3 37.6 0.5 53 1324 0 18.9 **** 270 *** * *** 12.0 1.4 36.6 0.4 54 1354 0 18.8 **** 261 *** * *** 11.9 1.4 36.2 0.5 55 1430 0 18.6 9.1 275 8.3 0 97 12.2 1.5 35.4 0.4 18 18.0 8.9 272 8.2 0 103 12.0 1.5 36.0 0.5 30 8.6 9.8 281 7.3 0 99 11.6 1.5 37.2 0.7 91 4.2 12.3 278 7.9 0 103 11.9 1.5 38.6 0.7 167 4.0 11.5 284 7.7 0 104 11.8 1.4 37.6 1.4 56 1505 0 18.8 **** 268 *** * *** 12.0 1.4 37.6 0.6 57 1628 0 19.0 9.2 271 8.4 3 100 11.6 1.4 36.2 0.5 21 18.5 8.7 251 8.3 1 100 12.0 1.4 35.7 0.6 31 9.6 9.4 280 7.6 0 102 11.6 1.4 38.6 0.9 91 4.2 11.5 285 7.7 0 103 11.4 1.3 38.9 1.3 Table 1 (Continued)

Tempera- Dissolved Specific Bicarbonate Total ture oxygen conductance pH alkalinity alkalinity (0 C) (ppm) o(18 x 107 (ppm CaCO,) (ppm CaCO,)

September 13 58 1732 0 18.8 **** 271 *** * *** 11.6 1.3 36.0 0.6 September 14 59 1015 0 18.3 8.6 276 8.4 1 101 12.6 1.3 37.0 0.6 17 18.1 8.7 277 8.4 2 101 12.5 1.3 35.3 0.7 18 ****I 8.0 283 8.1 0 103 **** *** **** *** 60 1128 0 18.6 9.0 265 8.5 4 101 12.0 1.3 37.5 0.6 18 18.7 8.6 264 8.4 3 102 12.0 1.3 35.6 0.6 25 8.5 9.6 273 7.4 0 101 12.0 1.4 37.7 1.0 45 4.9 12.0 285 7.9 0 105 11.7 1.4 38.3 0.9 86 4.1 11.0 282 7.8 0 105 11.9 1.4 38.9 1.7 61 1221 0 18.3 **** 267 *** * *** 12.0 1.3 37.8 0.7 62 1251 0 18.2 **** 266 *** * *** 12.3 1.2 36.6 0.6 63 1321 0 18.1 **** 268 *** * *** 12.1 1.2 37.7 0.9 64 1351 0 18.5 **** 264 *** * *** 13.0 1.3 38.3 0.7 65 1430 0 19.1 9.6 265 8.5 5 101 13.0 1.2 38.2 0.7 26 16.8 7.7 272 7.8 0 101 13.0 1.3 37.8 0.8 32 10.5 9.0 274 7.7 0 103 12.5 1.2 38.4 0.9 60 4.8 12.0 277 7.9 0 104 11.7 1.3 37.5 1.0 121 4.1 12.2 277 8.0 0 104 11.6 1.1 38.1 1.0 218 4.0 11.4 276 7.8 0 106 11.2 1.2 39.8 1.8 66 1619 0 19.1 **** 266 *** * *** 11.5 1.2 36.8 0.8 67 1649 0 19.1 **** 266 *** * *** 12.8 1.3 38.4 0.7 68 1719 0 19.0 **** 268 *** * *** 12.1 1.3 35.4 0.7 69 1802 0 19.4 9.1 268 8.6 5 102 11.4 1.2 35.8 0.7 17 19.4 8.2 452 8.2 0 99 34.0 1.6 51.3 0.7 September 16 70 0554 0 18.4 8.6 269 7.7 0 101 12.9 1.2 35.1 0.7 24 18.8 8.5 282 8.2 0 97 13.5 1.5 37.0 0.8 30 9.1 9.4 277 7.7 0 103 11.4 1.3 38.2 1.0 90 4.3 11.4 282 7.4 0 103 11.4 1.3 39.9 1.5 71 0638 0 18.3 8.8 282 8.3 3 100 14.3 1.3 36.8 0.7 24 14.9 8.0 270 7.4 0 101 13.5 1.5 36.4 0.7 30 9.8 9.0 279 7.3 0 99 11.9 1.4 38.4 0.8 90 4.2 12.1 280 7.8 0 102 12.0 1.4 39.1 0.9 178 3.9 11.0 280 7.7 0 105 11.8 1.3 38.9 2.0 72 0759 0 18.3 **** 273 *** * *** 11.9 1.3 36.2 0.7 73 0829 0 18.2 **** 277 *** * *** 11.5 1.3 36.4 0.7 74 0 18.1 9.0 270 8.3 1 97 11.9 1.3 35.1 0.8 10 18.5 9.1 274 8.2 0 97 12.3 1.3 36.7 0.9 75 1049 0 18.6 **** 269 *** * *** 11.9 1.4 34.6 0.7 76 1100 0 18.6 8.5 260 8.2 0 99 11.9 1.3 36.2 0.6 24 18.9 8.3 265 8.2 0 99 11.9 1.3 35.4 0.7 30 15.3 7.7 269 7.4 0 95 13.0 1.5 36.2 0.8 60 4.7 11.6 286 7.6 0 104 16.7 1.4 35.7 1.0 90 4.4 11.1 282 7.7 0 106 11.2 1.4 36.7 1.6 77 1144 0 18.4 **** 273 *** * *** 12.1 1.4 33.9 0.8 78 1224 0 18.5 8.9 273 8.5 4 101 12.6 1.4 36.2 0.8 18 18.5 8.5 281 8.2 0 100 13.2 1.5 36.8 0.9 79 1345 0 19.3 9.3 270 8.3 1 100 12.1 1.4 37.2 1.0 17 18.5 8.5 271 8.2 0 101 12.4 1.4 35.9 1.0 80 1425 0 18.7 **** 276 *** * *** 12.8 1.3 37.2 1.0 81 1450 0 19.3 8.9 267 8.3 1 97 13.1 1.3 37.0 1.1 18 18.1 7.9 269 8.0 0 99 12.7 1.2 37.9 1.3 18 ****I 7.2 288 7.8 0 *** **** *** **** *** September 17 82 0600 0 18.6 **** 268 *** * *** 12.3 1.2 36.5 1.2 83 0 18.2 **** 271 *** * *** 12.6 1.3 37.8 0.8 84 0700 0 17.7 **** 272 *** * *** 11.9 1.3 38.1 0.9 85 0721 0 17.7 9.0 271 8.2 0 101 12.3 1.5 39.1 0.9 24 14.3 7.4 282 7.7 0 102 12.4 1.4 40.0 1.3 31 11.0 7.3 287 7.5 0 104 12.3 1.3 40.5 1.8 86 0818 0 17.6 **** 261 *** * *** 12.5 1.2 38.2 0.8 87 0842 0 17.6 7.7 273 8.2 0 100 12.7 1.2 38.7 0.9 21 18.0 8.8 273 8.2 0 100 12.8 1.1 39.6 0.8 24 15.3 6.4 280 7.5 0 103 11.8 1.3 39.7 1.7 88 0938 0 17.5 **** 273 *** * *** 12.0 1.4 39.3 0.9 89 1010 0 17.4 8.6 268 8.1 0 100 12.6 1.4 40.0 0.9 23 17.4 8.5 269 7.9 0 100 12.5 1.4 39.8 1.1 28 14.3 5.5 281 7.6 0 104 12.5 1.4 42.1 2.1 29 ****I 4.4 286 7.4 0 105 **** *** **** *** 90 1058 0 17.4 **** 275 *** * *** 12.9 1.4 38.6 0.8 91 1134 0 17.6 8.8 270 8.2 0 102 12.8 1.3 41.0 1.1 Table 1 (Continued

Tempera- Dissolved Specific Bicarbonate Total ture wren conductance pH alkalinity alkalinity (0 C) (ppm) o(18 x 109 (ppm CaCOa) (ppm CaCOa)

September 17 17 16.9 7.7 274 7.6 99 13.0 1.3 40.2 1.5 27 11.6 3.0 281 7.1 107 12.6 1.3 41.8 3.4 27 ****' 3.0 282 7.2 107 **** *** **** *** 92 1240 0 17.5 8.7 268 8.2 102 12.0 1.3 41.7 1.2 18 16.9 6.9 276 7.6 102 12.2 1.3 41.1 1.8 September 18 93 0615 0 17.3 **** 276 *** * *** 12.2 1.3 39.0 0.9 94 0645 0 17.1 **** 278 *** * *** 11.7 1.3 37.8 1.0 95 0730 0 17.4 8.5 267 8.3 0 102 12.2 1.3 37.7 0.8 24 16.0 7.3 272 8.0 0 104 11.9 1.3 38.5 1.2 31 11.7 3.9 291 7.6 0 111 12.5 1.3 41.7 3.4 96 0812 0 17.2 **** 272 *** * *** 12.2 1.3 38.6 1.1 97 0842 0 ****' **** 273 *** * *** 11.9 1.3 37.7 0.9 98 0912 0 17.1 **** 276 *** * *** 11.7 1.3 36.6 0.9 99 0930 0 17.7 8.7 270 8.3 3 101 11.9 1.2 37.7 0.8 27 17.6 8.7 276 8.2 0 101 11.9 1.3 37.7 0.7 32 16.1 8.4 270 8.1 0 103 11.7 1.2 37.0 1.1 45 16.3 9.8 292 7.7 0 107 11.9 1.2 39.3 1.8 100 1027 0 17.9 **** 264 *** * *** 11.6 1.3 35.9 0.8 101 1047 0 18.0 9.0 261 8.4 2 100 11.2 1.3 36.2 0.8 31 18.0 8.5 268 8.2 * 103 12.4 1.3 36.2 1.0 33 17.1 8.1 274 8.1 * 102 11.3 1.3 35.8 0.8 61 5.8 10.2 283 7.7 * 110 11.1 1.2 38.1 1.6 91 5.1 10.2 284 7.7 * 109 11.4 1.3 38.6 1.8 102 1137 0 18.1 **** 269 *** * *** 11.1 1.2 37.1 0.5 103 1207 0 18.3 **** 271 *** * *** 11.9 1.2 36.6 0.8 104 1237 0 18.5 **** 271 *** * *** 13.0 1.3 36.5 0.7 105 1307 0 18.5 **** 270 *** * *** 12.5 1.3 34.7 0.8 106 1337 0 18.5 **** 318 *** * *** 20.7 1.5 40.5 0.8

'Water collected with horizontal sampler; no temperature measurement. Table 2. Chemical and physical measurements (averages and ranges) for surface and subsurface water of Lake Ontario, September 8-18, 1964

All depths Surface Subsurface Item Average Range Average Range Average Range

Oxygen @w-d 9.57 3.0-12.3 9.29 7.7-10.4 9.66 3.0-12.3 PR 7.94 7.1-8.6 8.32 7.7-9.8 7.81 7.1-8.4

Bicarbonate alkalinity 0.8 o-s 2.5 o-s 0.1 o-4 @pm CaC03) Total alkalinity 101.7 95-111 100.1 96-104 102.2 95-111 @pm CaCQ)

Conductivity 277.0 251-452 271.3 257-318 281.6 251-452 (pmhos at 180 C)

Sodium (ppm) 12.0 10.4-34.0 12.04 10.4-20.7 11.96 10.5-34.0

Potassium (ppm) 1.26 0.8-1.6 1.24 0.8-1.5 1.27 1.0-1.6

Calcium (ppm) 38.18 33.9-51.3 37.57 33.9-42.5 38.7 35.3-51.3

Silica (ppm) 0.91 0.4-3.4 0.71 0.4-1.2 1.08 0.5-3.4 Ranges which excluded extreme values were chosen by in- spection of frequency distributions for all values for each con- stituent. The exclusion of extreme values permitted a better representation of the chemical composition of the open waters of the lake. The data were further divided by location to represent the western (stations l-45) and eastern (stations 46-106) portions of the lake. Averages, ranges, and the percentage of the data falling within the selected ranges were computed according to depth and area of the lake (Table 3). Data for pH, oxygen, bicarbonate alkalinity, and total alkalinity are not included because the range in values was small or, as for oxygen, the values falling outside the normal range could not be regarded as abnormal. The average values for the selected samples changed little (about 3%) from the original averages, but for all constituents except potassium the range was greatly reduced (Tables 2 and 3). To determine if significant east-west or surface-subsurface differences existed, mean values were compared in t-tests (Table 4). The 0.001 level or probability was selected because of the small variation within groups. Although average surface oxygen concentrations were significantly different between the eastern (8.85 ppm) and western (9.76 ppm) portions of the lake, the differences may reflect meteoro- logical conditions during the sampling period. Although surface and subsurface averages differed for pH, bicarbonate, and total alkalinity, differences between the eastern and western portions of the lake were not significant. Comparisons of the selected values of potassium showed no difference by depth or area of the lake. The average concentration of potassium (1.26 ppm) is probably representative of all depths and both areas. Differences in values of calcium and conductivity were significant between the surface and subsurface and between the eastern and western areas of the lake. Average concentrations of sodium for the surface (11.95 ppm) and subsurface (11.74 ppm) were not significantly different; however, an east- west discrepancy (average concentrations of 12.05 ppm in the east and 11.64 ppm in the west) was significant. As expected, surface silica concentrations (0.71 ppm average) were significantly lower than the subsurface concentrations (1.03 ppm average). Silica was significantly higher in the east only in surface samples. This difference may indicate that the primary productivity of Lake On- tario differed significantly between the eastern and western portions of the lake, at least during the sampling period. The highest silica concentration, 3.4 ppm, was in two samples collected near the bottom at stations 91 and 95. Both stations are in the extreme northeast end of the lake, are relatively shallow, and have low dissolved oxygen. The high concentration of silica and low concentration of dissolved oxygen may be due to the suspension Table 3. Selected chemical and physical measurements (averages and ranges) for surface and subsurface water of Lake Ontario, September 8-18, 1964

All depths Surface Subsurface m Average Range Percentage’ Average Range Percentage1 Average Range Percentage l Conductivity (pmhos at 18° C) All samples 276.2 264-292 95 271.5 264-289 93 279.9 264-292 96 Western samples 278.0 264-292 95 272.6 264-289 96 281.3 267-292 95 Eastern samples 274.4 264-292 94 270.7 264-282 92 278.2 264-292 97 Sodium (ppm) All samples 11.84 10.8-13.2 96 11.95 11.1-13.1 97 11.74 10.8-13.2 95 Western samples 11.64 10.8-13.1 97 11.79 11.1-12.6 98 11.55 10.8-13.1 97 Eastern samples 12.05 10.8-13.2 95 12.08 11.1-13.1 97 12.02 11.1-13.2 92 Potassium (ppm) All samples 1.26 1.0-1.6 99 1.25 1.0-1.5 98 1.27 1.0-1.6 100 Western samples 1.24 LO-l.5 98 1.22 1.0-1.4 96 1.26 1.0-1.5 100 Eastern samples 1.28 1.0-1.6 100 1.28 1.1-1.5 100 1.29 1.0-1.6 100 Calcium (ppm) All samples 38.09 35.3-41.3 92 37.68 35.3-41.2 90 38.42 35.3-41.3 94 Western samples 38.46 35.3-41.3 93 37.99 35.3-41.2 89 38.74 35.4-41.3 96 Eastern samples 37.67 35.3-41.1 91 37.44 35.4-41.0 90 37.94 35.3-41.1 92 lica (ppm) All samples 0.88 0.4-1.8 98 0.71 0.4-1.2 100 1.03 0.5-1.8 97 Western samples 0.86 0.4-1.8 100 0.65 0.4-0.9 100 0.99 0.6-1.8 100 Eastern samples 0.90 0.4-1.8 96 0.76 0.4-1.2 100 1.09 0.5-1.8 92 Percentage of total observations. Table 4. Average chemical and physical measurements of Lake Ontario according to depth and area [Opposing arrows indicate significant different means; facing arrows indicate nonsignificant means (0.001 level of probability).]

‘Average values from Table 3. of bottom material in the water column during storms. Suther- land et al. (1966) reported that the silica concentration of the interstitial water, which may be in thermodynamic equilibrium with the sediment, is 50 to 200 times higher than that in Lake Ontario water. Average values determined in the present and other studies are compared in Table 5. (The data of the International Joint Commission [1951], Rodgers [1962], and the Great Lakes Institute [1965] are not represented because they did not include values for any of the major cations.) Silica concentrations reported by Sutherland et al. (1966) for November and January range from 0.15 to 0.6 ppm. With the exception of silica, the data ‘from the Bureau of Commercial Fisheries survey in 1961 near the mouth of the Niagara River are similar to those of the present study. Differences in silica concentration between the 1961 and 1964 surveys may be due to the relatively small study area in 1961 or to differences in the method of analysis. A silicomolybdate method was used for the analysis of the 1961 samples whereas a heteropoly blue method was used for the 1964 samples. Suther- land et al. (1966) also employed a silicomolybdate procedure and obtained results in general agreement with the Bureau’s 1961 study. Lake Ontario is chemically similar to Lake Erie from which it receives about 85% of its water. Calcium and sodium were less than 2 ppm higher, silica was about 0.5 ppm lower, and potassium was less than 0.2 ppm lower than in Lake Erie (Beeton and Chandler, 1963). The chemical composition has changed more rapidly and to a greater degree since 1920 in Lakes On- tario and Erie than in the other Great Lakes (Beeton, 1965). Rates of increase of dissolved solids, calcium, sodium-plus-potassium, and chloride in Lake Ontario have closely paralleled increases in Lake Erie but the rate of increase in sulfate was 1.4 times greater in Lake Ontario than in Lake Erie between 1930 and 1960. Most of the increases in chemical content in Lake Ontario are attributable to changes in the quality of water from Lake Erie.

Dissolved Oxygen

Oxygen depletion in the open waters of Lake Ontario is not serious. In contrast, the concentration of dissolved oxygen in Lake Erie was less than 1.0 ppm near the bottom of about 1,390 square miles of the central basin in 1959 and 641 square miles in 1960 (Carr, 1962). The difference is directly attributable to differences in the depths of the two lakes. The central basin of Lake Erie is relatively shallow (mean depth, 18.5 m) and thermal stratification Table 5. Average chemical values of Lake Ontario reported by various authors

Year of Total alkalinity K+ Ca++ SiOa Conductivity Study observation (pw CaCO,) (ppm) (ppm) @pm) (Mmhos at 18° C)

Bureau of Commercial Fisheries ‘1961 10.8 1.2 39.3 0.3 272

Kramer (1962) 1959 95.5 9.5 1.8 38.8

Dobson (1967) 1966 94.0 12.2 1.44 42.9 270

Present study 1964 101.7 11.84 1.26 38.09 0.88 276.2

‘Unpublished data of this laboratory collected near the Niagara River. usually is stable 15 to 17 m below the surface. Since the average depth of Lake Ontario is 83 m, the ratio between the height of the hypolimnion of Lake Ontario and that of the central basin of Lake Erie is about 25:1. The amount of dissolved oxygen present in the hypolimnetic waters of Lake Ontario at the begin- ning of thermal stratification, therefore, is 25 times that of Lake Erie. If the depletion of oxygen in Lake Ontario is due to the sediments as it is in Lake Erie (Carr et al., 1963), it would take longer for all the oxygen in the hypolimnion of Lake Ontario to be consumed than the period of stratification. The oxygen de- mand and the rate of consumption of oxygen by Lake Ontario sediments are probably less than that of Lake Erie since the water temperatures are lower and less material from algal or pollu- tional sources are present. Oxygen depletion was greatest in the extreme northeast por- tion of Lake Ontario. The lowest measured concentration of dissolved oxygen (3.0 ppm, 27% saturation) was in the north channel north of Amherst Island (station 91). Concentrations were also low at stations 89 and 95 (4.4 ppm, 42% saturation and 3.9 ppm, 35% saturation, respectively) near Amherst Island. At these stations extension of the metalimnion to within 1.5 m of the bottom left only a small reserve of hypolimnetic oxygen to be consumed by the sediment. Oxygen depletion in the deepest waters of Lake Ontario is small. The dissolved oxygen at 218 m (station 65), in the deepest area in Lake Ontario, was 86.5% saturation (11.4 ppm). In comparison, dissolved oxygen in the “deep hole” (65 m) of Lake Erie was as low as 47% of saturation in September (Carr, 1962). The oxygen depletion at the deepest station in Lake Ontario, which has a hypolimnetic height three times the average, should be only 0.4 ppm if the water is saturated at the time of stratification. Although the depletion was 1.8 ppm at 218 m, the depletion was only 1.0 ppm (92.7% saturation) at 121 m, which indicates that the hypolimnetic waters are not thoroughly mixed. Dobson (1967) indicated that oxygen saturation in the deepest waters in Lake On- tario was 95% in late June 1966. The depletion of oxygen in the open waters of Lake Ontario cannot be considered critical.

Literature Cited

AMERICAN PUBLIC HEALTH ASSOCIATION. 1965. Standard methods for the examination of water and waste water. 12th Ed., American Public Health Association, Inc., New York, 769 p. BEETON, ALFRED M. 1965. Eutrophication of the St. Lawrence Great Lakes. Limnol. Oceanogr., 7:240-254. BEETON, ALFRED M. and DAVID C. CHANDLER. 1963. The St. Lawrence Great Lakes. Zn: Frey, D. G. (Ed.,), Lim- nology in North America. Univ. Wisconsin Press, Madison, Wisconsin, p. 535-558. CARR, JOHN F. 1962. Dissolved oxygen in Lake Erie, past and present. Univ. Mich., Great Lakes Res. Div., Pub. 9:1-14. CARR, J. F., A. M. BEETON, and H. ALLEN. 1963. Factors associated with low dissolved oxygen concentrations in Lake Erie. Univ. Mich., Great Lakes Res. Div., Pub. 10:133 (Abstract). DOBSON, HUGH H. 1967, Principal ions and dissolved oxygen in Lake Ontario. Proc. 10th Conf. Great Lakes Res., Int. Assoc. for Great Lakes Res., p. 337-356. GREAT LAKES INSTITUTE. 1965. Great Lakes Institute data record-1963 surveys. Part I: Lake Ontario, Lake Erie, and Lake St. Clair. Report PR 23, 195 p. HILTUNEN, JARL K. 1969. The benthic macrofauna of Lake Ontario. Great Lakes Fish. Comm. Tech. Rept. No. 14. p. 39-50. INTERNATIONAL JOINT COMMISSION. 1951. Report of the International Joint Commission, United States, and Canada on pollution of boundary waters. Washington and Ottawa, 312 p. JOERIS, LEONARD S. 1964. A horizontal sampler for collection of water samples near the bottom. Limnol. Oceanogr., 9:595-598. KRAMER, J. R. 1962. Chemistry of western Lake Ontario. Univ. Mich., Great Lakes Res. Div., Pub. 9:21-28. RODGERS, G. K. 1962. Lake Ontario Data Report 1961. Great Lakes Institute, Univ. of Toronto Preliminary Rept. No. 7, 102 p. SMITH, STANFORD H. 1962. Temperature correction in conductivity measurements. Limnol. Oceanogr., 7:330-334. SUTHERLAND, JEFFREY C., JAMES R. KRAMER, LEE NICHOLS, and TIMOTHY D. KURTZ. 1966. Mineral-water equilibria, Great Lakes: Silica and phosphorus, Univ. Mich., Great Lakes Res. Div., Pub. 15:439-445.

18 PLANKTONIC DIATOMS OF LAKE ONTARIO’

Jerry F. Reinwand U.S. Bureau of Commercial Fisheries Biological Laboratory Ann Arbor, Michigan

ABSTRACT

The major species of diatoms in surface collections from Lake On- tario in September 1964 were Asterionella formosa, Fragilaria crotonensis, and Tabellaris fenestrata. Dominant species in the deep-water samples were Stephanodiscus astraea, S. astraea var. mintula, and F. crotonensis. The diatom flora in surface collections varied among several stations in the eastern end of the lake.

Introduction

Studies of the phytoplankton of Lake Ontario are few. Tucker (1948) studied the summer populations of phytoplankton in the Bay of Quinte but did not make taxonomic determinations to species. Schenk and Thompson (1965) evaluated data gathered at the Toron- to Island Filtration Plant in 1923-54 and listed generic names of the dominant diatoms. Nalewajko (1966a) made a comprehensive, 19-month investigation of phytoplankton populations in 1964-65. The present study gives more information on the distribution and abundance of planktonic diatoms of Lake Ontario and provides a base for future comparisons.

Methods and Materials

Water samples were collected with Nansen bottles from 24 stations (Fig. 1) at various depths. To simplify the comparisons of lakewide diatom populations, three strata of water were established: “surface,” which included

‘Contribution No. 387, Ann Arbor Biological Laboratory, U.S. Bureau of Commercial Fisheries. Figure 1. Lake Ontario, showing sampling stations for diatoms. all samples from the surface to 5 meters; “intermediate,” which included samples from 9 to 45 meters; and “bottom,” which included collections from 90 to 220 meters. All plankton samples were preserved by the method described by Utermijhl (1958). A sample of 80° ml was passed through a 47 mm2 membrane filter. The filter was inserted into a 20 ml glass vial and dissolved in acetone to release the diatoms. Dia- toms were cleaned and prepared by the method of Hohn and Hellerman (1963). Diatoms were examined at 970 X with an oil immersion lens; they were counted by starting at one edge of the coverslip and viewing a row 159p wide across the width of the coverslip. Each valve was counted as one-half frustule; broken valves were not included. If fewer than 150 frustules were recorded, another row was counted. Quantitative determinations were made by direct proportion. Several small centric diatoms were difficult to identify to species, especially those of the genus Stephanodiscus. Considerable confusion exists regarding the taxonomic treatment of these small centric species. I have examined Nalewajko’s (1966a) Lake On- tario cultures of S. tenuis Hust. and compared them with Stoermer and Kopezynska’s (1967) samples and data from Lake Michigan. S. tenuis and Thalassiosira nana Lohmann apparently are both in Lake Ontario but I found it very difficult to discern differences between the species. I, therefore, have grouped them under S. tenuis. Whenever possible, diatoms were identified to species but those taxa which could not be positively identified were assigned a tentative name. The following species were identified (asterisks indicate tentative identification): Achnanthes clevei Grun. Gyrosigma attenuatum (Kütz.) Rabh. A. Lanceolata (Breb.) Grun. Melosira ambigua (Grun.) 0. Müll. Amphiprora o nata Bailey M. binderana Kütz. Amphora ovalis Kütz. M. granulata (Ehr.) Ralfs. A. ovalis var. pediculus Kütz. M. islandica 0. Müll. Asterionella formosa Hass. M. italica (Ehr.) Kütz. Caloneis bacillum (Grun.) Cleve Navicula anglica Ralfs. Cocconeis pediculus Ehr. N. cryptocephala Kütz. C. placentula Ehr. var. placentula *N. menisculus Schum. Coscinodiscus radiatus Ehr. N. radiosa Kütz. *Cyclotella atomus Hust. Nitzschia acicularis W. Sm. *C. comta (Ehr.) Kütz. N. dissipata (Kütz.) Grun. C. kutzingiana Thwaites N. holsatica Hust. C. meneghiniana Kütz. N. sigmoidea (Ehr.) W. Sm. C. pseudostelligera Hust Rhoicosphenia curvata (Kütz.) Grun. C. stelligera Cleve & Grun. Stephanodiscus astraea (Ehr.) Grun. Cymatopleura elliptica var. hiber- S. astraea var. minutula (Kütz.) nica (W. Sm.) Hust. GlXUl. Cymbella affinis Kütz. *S. hantzschii Grun. C. microcephala Grun. S. niagarae Ehr. Diatoma tenue var. elongatum *S. tenuis Hust. Lyngb. Surirella ovata Kütz. Fragilaria capucina Desm. Synedra acus Kütz. F. crotonensis Kitton. S. ulna (Nitzsch) Ehr. Gomphonema olivaceium (Lyngb.) Tabellaria fenestrata (Lyngb.) Kutz. Kütz. C. parvulum (Kütz.) Kütz. T. ftocculosa (Roth) Kütz.

Abundance and Species Composition

Diatom numbers were low throughout the lake during Septem- ber 8-18, 1964 (Table 1). Highest counts in collections from different strata were 204 cells/ml at the surface (station 32, Fig. 2), 220 cells/ml at intermediate depths (station 78, Fig. 3), and 257 cells/ml at the bottom (station 35, Fig. 4). Diatoms were generally more abundant near the shore. Nalewajko (1966a) also found low diatom numbers (15 cells/ml) in surface samples collected on September 18, 1964. The species composition of diatoms in the present study differed in the surface and bottom collections. Asterionella formosa, Fragilaria crotonensis and Tabellaria fenestrata were generally dominant species at the surface (Fig. 2) whereas Stephanodiscus astraea, S. astraea var. minutula, and F. crotonensis, predomi- nated in the deepest samples (Fig. 4). Stoermer and Kopczynska (1967) found a uniform distribution of phytoplankton throughout the water column in Lake Michigan in spring collections but numbers were higher in or just below the thermocline in the fall. Variation of the surface diatom flora was evident at several eastern stations. Fragilaria capucina, which was either absent or rare at the western and central stations, was among the best represented species at most eastern station. Nalewajko (1966a) Table 1. Abundance (cells/ml) of major diatom species in collection from Lake Ontario, September 8-18, 1964

0 8.0 -36.0 - 0.7 - -2.0 - 2.7 0.7 - 8.7 13.3 74.1 11 11.3 - 55.4 - 0.1 -- _ - 1.4 0.7 - 2.6 10.0 84.7 13 3.3 2.0 30.7 ------_ 0.6 - 0.6 9.3 48.0 7 0 16.1 2.0 35.4 -- 0.1 - _ _ 0.1 1.3 - 2.6 10.0 69.5 18 14.0 - 88.1 ---- - 0.1 2.0 2.7 16.1 135.6 100 14.0 1.3 37.3 -- 0.6 - 1.3 7.3 4.7 5::; - 16.0 20.7 161.6 11 0 12.1 11.3 30.7 ---- _ _ 1.3 - 9.3 22.0 34.1 18 - 2.0 21.7 -- 2.1 - 0.1 2.0 4.1 6.1 - 2.0 5.4 48.8 17 0 8.1 2.7 67.4 -- 1.4 - - 2.1 2.7 - 18.1 18.0 152.2 9 30.6 10.7 33.3 -- 1.3 - - 1.9 1.9 14.7 - 21.3 25.3 148.8 18 0 15.4 10.0 30.7 ---- - 0.7 2.0 - 9.4 18.1 87.5 11 4.6 6.0 17.3 ---- _ _ 0.7 1.3 - 0.7 11.3 42.6 so -- 4.7 -- 4.0 - 0.7 0.1 0.4 2.0 - 0.1 2.0 20.0 28 0 2.7 - 33.3 -- 2.0 - 0.1 9.3 48.6 12 12.0 - 38.0 ---- _ _ --- - 25.3 76.1 142 - 4.0 12.6 -- 2.7 - 5.3 2.6 5.3 26.0 - 6.0 2.6 10.7 32 0 5.9 1.2 118.9 0.6 14.1 0.6 - - 0.6 15.3 4.7 1.2 6.7 29.4 204.3 16 2.0 - 54.1 ---- _ - 4.6 6.0 0.7 2.0 18.0 87.5 33 0 5.3 - 43.3 ---- 0.6 - - 14.7 64.7 15 4.0 - 18.1 ---- _ _ 0.6 - - 23.4 46.7 91 1.9 10.7 12.6 1.3 1.9 4.0 - 1.9 1.9 26.1 74.8 0.6 11.3 6.6 161.6 35 0 3.3 - 37.4 - 0.6 - 0.6 16.0 58.1 15 6.0 - 82.1 - 0.7 - - 22.6 112.7 180 - 2.6 12.0 - 12.6 67.3 2.6 - 5.9 88.1 34.7 2.6 4.1 8.7 256.9 38 0 6.1 2.0 23.4 - --- _ - 1.3 - - 15.4 49.5 12 14.0 - 60.1 - - 2.0 - - 17.3 94.7 97 0.7 - 21.4 - - 21.4 1.4 2.1 4.1 41.4 58.7 - 2.1 10.1 166.8 40 0 25.3 2.6 29.3 - _ _ _ _ - 0.6 4.6 - 0.6 37.3 105.5 18 9.4 13.3 34.8 - - 6.7 - - 4.6 11.4 - 0.1 30.7 140.2 45 - 0.6 - - 0.6 4.0 - 1.3 18.7 59.5 3: 10.7 4.0 - - 1946:7 - - - 1.4 - 1.3 - 1.4 8.0 - 2.0 17.4 50.1 50 0 11.3 2.7 28.0 - - 0.6 - 0.6 0.6 2.0 1.3 0.6 1.3 10.1 12.7 18 12.6 16.7 54.7 - _ _ - - 1.3 7.3 0.6 - 27.4 121.6 55 0 15.3 - 44.7 - - 0.7 -- - 84.1 30 6.7 4.0 48.7 - 1.4 - - 30.0 90.7 169 1.3 - 7.3 - 0.7 5.4 - 0.6 2.0 8.0 52.0 - 4.6 8.6 94.1 59 0 8.0 - 12.2 - - 1.4 - - 0.6 3.4 0.6 4.0 11.4 105.5 11 2.0 - 48.1 - - 2.1 - 0.7 32.0 88.1 65 0 3.4 8.0 56.3 1.3 6.6 - 4.0 8.0 88.7 30 4.6 6.6 20.6 - _ _ _ 1.3 - - 5.3 38.6 220 0.7 - 19.4 - - 4.6 0.7 - 0.7 15.3 14.6 - 2.0 3.4 62.1 71 0 1.3 8.0 7.4 - 0.7 - 1.3 1.3 21.4 30 2.1 - 31.4 - - 0.6 - - 0.6 -- - 4.1 46.7 118 -- 1.3 - 1.3 2.0 - 2.0 5.3 1.3 54.1 - 0.7 - 74.7 74 0 4.6 - 21.4 - - 1.3 - - 2.0 10.0 - 4.0 7.4 51.5 10 0.6 - 30.0 - - 2.0 12.0 - 0.6 8.6 58.1 78 0 2.6 35.3 28.0 2.0 4.0 3.4 - - 1.3 16.0 - 4.7 6.6 108.7 18 7.3 58.2 81.5 - - 1.3 - 0.1 - 14.1 27.3 - 4.0 11.4 220.3 81 0 1.3 104.7 18.0 14.6 - 6.1 4.0 1.4 2.7 4.0' 180.2 85 0 0.3 8.0 16.0 - 0.3 -- - 0.4 3.3 0.2 2.6 8.0 44.1 31 9.4 34.1 50.8 - 2.0 1.3 - _ _ 2.0 6.0 1.3 0.6 8.1 130.2 81 5 8.6 20.7 56.8 - - 0.7 0.1 6.0 1.3 1.3 16.1 116.8 91 5 14.1 71.4 38.7 - - 0.6 0.6 31.9 0.6 5.3 164.8 99 0 4.0 10.7 19.4 - - 10.1 48.1 45 0.7 86 12.6 1.3 5.3 5.3 0.7 0.7 6.0 44.7 56.7 -2.0 8.6 166.2 Figure 2. Species composition of diatoms in surface collections, Septem- ber 8-18, 1964.

Figure 3. Species composition of diatoms at intermediate depths, Septem- ber 8-18, 1964.

recorded very low numbers of F. capucina in her year-round collections off Gibraltar Point and reported none at two eastern stations during April 26-28, 1965. Holland (1965) reported that F. capucina contributed 7% of the total diatom population in the Apostle Islands region of Lake Superior but did not exceed 5% of the total in collections from the rest of the lake. Stoermer and Kopczynska (1967) found F. capucina in fairly low numbers at a few stations in Lake Michigan in August-September 1962. Several investigators (Burkholder, 1960; Hohn, 1966; Verduin, 1964, and Figure 4. Species composition of diatoms in deep-water samples, Septem- ber 8-18, 1964.

Wujek, 1967) have emphasized the significance of F. capucina in the diatom flora of Lake Erie and its tributaries. Stephanodiscus niagarae composed 19% of the total diatom population at station 91, but was insignificant at the other stations. The contribution of S. niagarae to the total biomass of diatoms is not adequately assessed on a numerical basis because of its large cell volume. Several investigators (Cowell, 1960; Davis, 1954; Lund, 1961, 1964; Nalewajko, 1966b; Rawson, 1956; Verduin, 1954; and Wujek, 1966) have indicated that volume or dry weight of phytoplankton may be a better criterion than enum- eration to evaluate productivity. Melosira ambigua and M. granulata were sparse or absent at most stations, but were common at station 81. Nalewajko (1966a) reported that Melosira binderana and M. islandica were the two most important species in her year-round collections. M. binderana and M. islandica were collected in the present study, but usually only in the bottom strata. Their presence near the bottom may reflect spring or early summer increases of these species which then sank into the deeper waters after thermal stratification. Lund (1954) demonstrated this phenomenon in certain lakes in England for M. italica subsp. subarctica. He reviewed data collected by Rawson for Great Slave Lake (Lund, 1962) and concluded that periodicity of M. islandica is ” . . . intimately bound to the changes in the vertical distribution of water density.” This same phenomenon may explain the predominance of S. astraea and S. astraea var. minutula in the deepest stations of this study. Nalewajko (1966a) stated that “A very small form of Stephanodiscus astraea (Ehr.) Grun., only 8~ in diameter was very common but was not counted”; she did, however, give data for S. astraea which was most abundant in April and May. Melosira italica was recorded at several stations but in very low numbers. I believe the species is new to the list of Lake Ontario diatoms but this belief is difficult to verify, because as Stoermer and Kopczynska (1967) noted for Lake Michigan taxa, “Definitive treatments of some of the dominant groups are entirely lacking, and this is reflected in the confusion of nomenclature that exists between the various publications.” Stephanodiscus tenuis was common in surface collections at station 17 (maximum count was 48 cells/ml) but, in general, the abundance of this species was low throughout the lake. S. tenuis was the most abundant plankter of Nalewajko’s (1966a) investigation, and was very common (5,191 cells/ml) during the spring pulse of 1965. M. H. Hohn (personal communication) has also found S. tenuis to be a common component of the diatom flora of western Lake Erie. The records for S. tenuis demonstrate the value of year-round sampling for the accurate interpretation of phytoplankton populations. Asterionella formosa and Tabellaria fenestrata were ubiqui- tous in surface samples of the present study, These species are important components of the diatom flora of the Great Lakes and probably tolerate a wide range of ecological conditions. Nalewaj- ko’s (1966a) collections included T. flocculosa but not T. fenestrata. Only two cells of T. flocculosa were observed in the present investigation. Acknowledgments I thank M. H. Hohn and E. F. Stoermer for their assistance in taxonomic determinations of the difficult diatom species. Literature Cited

BURKHOLDER, PAUL R. 1960. A survey of the microplankton of Lake Erie. In: Limnological Survey of eastern and central Lake Erie, 1928-29. U.S. Fish Wildl. Serv., Spec. Sci. Rept., Fish. No. 334:123-144. COWELL, BRUCE C. 1960, A quantitative study of the winter plankton of Urschel’s Quar- ry. Ohio J. Sci., 60:183-191. DAVIS, CHARLES C. 1954. A preliminary study of the plankton of the Cleveland Harbor area, Ohio. II. The distribution and quantity of the phytoplankton. Ecol. Monogr., 24:321-347. HOHN, MATTHEW H. 1966. Analysis of plankton ingested by Stizostedium [sic] vitreum vitreum (Mitchill) fry and concurrent vertical plankton tows from southwestern Lake Erie, May 1961 and May 1962. Ohio J. Sci., 66:193-197. HOHN, MATTHEW H. and JOAN HELLERMAN. 1963. The taxonomy and structure of diatom populations from three eastern North American rivers using three sampling methods. Trans. Amer. Microsc. Soc., 82:250-329. HOLLAND, RUTH E. 1965. The distribution and abundance of planktonic diatoms in Lake Superior. Univ. Mich., Inst. Sci. and Tech., Great Lakes Res. Div., Pub. 13, pp. 96-105. LUND, J. W. G. 1954. The seasonal cycle of the plankton diatom Melosira italica subsp. subarctica 0. Müll. J. Ecol., 42:151-179. 1961. The periodicity of p algae in 3 English lakes. Verh. Int. Ver. Limnol., 14:147-154. 1962. The periodicity of Melosira islandica 0. Müll. in Great Slave Lake. J. Fish. Res. Bd. Canada, 19:501-504. 1964. Primary production and periodicity of phytoplankton. Verh. Int. Ver. Limnol., 15:37-56. NALEWAJKO, C. 1966a. Composition of phytoplankton in surface waters of Lake On- tario. J. Fish. Res. Bd. Canada, 23:1715-1725. 1966b. Dry weight, ash, and volume data for some freshwater planktonic algae. J. Fish. Res. Bd. Canada, 23:1285-1288. RAWSON, D. S. 1956. Algal indicators of trophic lake types. Limnol. Oceanogr., 1: 18-25. SCHENK, C. F. and R. I?. THOMPSON. 1965. Long-term changes in water chemistry and abundance of plankton at a single sampling location in Lake Ontario. Univ. Mich., Inst. Sci. and Tech., Great Lakes Res. Div., Pub. 13, pp. 197- 208. STOERMER, E. F. and E. KOPCZYNSKA. 1967. Phytoplankton populations in the extreme southern basin of Lake Michigan, 1962-1963. In: Proc. Tenth Conf. Great Lakes Res., Int. Assoc. Great Lakes Res., pp. 88-106. TUCKER, ALLAN. 1948. The phytoplankton of the Bay of Quinte. Trans. Amer. Microsc. Soc., 67:365-383. UNTERMOHL, HANS. 1958. Zur Vervollkommungder quantitativen Phytoplankton-Methodik. Int. Ver. Limnol., Mitt. 9:1-38. VERDUIN, JACOB. 1954. Phytoplankton and turbidity in western Lake Erie. Ecology, 35:505-561. 1964. Changes in western Lake Erie during the period 1948-1962. Verh. Int. Ver. Limnol., 15:639-643. WUJEK, DANIEL E. 1966. Seasonal variation in number and volume of plankton diatoms. Trans. Amer. Microsc. Soc., 85:541-547. 1967. Some plankton diatoms from the Detroit River and the western end of Lake Erie adjacent to the Detroit River. Ohio J. Sci., 67:32-35. LAKE ONTARIO PHYTOPLANKTON, SEPTEMBER 1964’

Roann E. Ogawa U.S. Bureau of Commercial Fisheries Biological Laboratory Ann Arbor, Michigan

ABSTRACT

Phytoplankton counts on samples collected in Lake Ontario on Septem- ber 8-18, 1964, showed that green algae were the dominant plankters and diatoms were of secondary importance. The greatest abundance of phytoplankton was close to shore from Toronto, along the southern shore of the lake, and up the eastern shore to the North Channel. The open waters of Lake Ontario were characterized by low numbers of phytoplankton. The relationships among phytoplankton abundance, bottom fauna distribution, and enrichment are discussed.

Introduction

The phytoplankton of Lake Ontario unlike that in adjoining Lake Erie has received little attention; the only comprehensive study was that of Nalewajko, 1966. Other investigations have been limited, either in area or scope (Tucker, 1948; Schenk and Thomp- son, 1965; McCombie, 1967; and Nalewajko, 1967). The present study, although limited by the short sampling period, covered the entire lake and revealed probable relationships among phytoplankton, bottom fauna, and enrichment.

Methods

Fifty-two samples were collected in Nansen bottles at 23 stations at various depths in Lake Ontario (Fig. 1). A sample of 800 ml from each depth was preserved with Lugol’s iodine-potassium iodide solution. Samples were concentrated by allowing the phytoplankton to settle, then reduced to 50 ml by drawing off the supernatant. One milliliter of the thoroughly mixed concentrate

‘Contribution No. 388, Ann Arbor Biological Laboratory, U.S. Bureau of Commercial Fisheries.

27 Figure 1. Sampling stations for total phytoplankton. Dotted line delineates the 5-mile inshore waters of the lake from open waters. was put into a Sedgewick-Rafter cell and counted with a 20X ob- jective and 10X eyepiece. Phytoplankton were counted in one row of the S-R cell if the number of organisms was approximately 500 or greater, and in two rows if the count was substantially less than 500. The field counted was delineated by a Whipple micrometer, 355~ wide, which was calibrated to the microscope. Counts are expressed as the number of cells/ml. Most of the phytoplankton were identified to species at 200X at the time of counting. Because small plankters cannot be identified to species at 200X, they were identified to genera. Flagel- lates belonging to the Euglenophyceae were identified only to class. Their small size and the loss of identifying characteristics due to preservation prevented more accurate identification. Diatoms were identified as centrics or pennates. A more detailed account of the diatom population was given by Reinwand (1969).

Total Phytoplankton

Total phytoplankton counts were low (Tables 1, 2, and 3). The number of cells/ml ranged from 257 to 1,755 at the surface (ex- cluding the count of 2,516 at station 81 in Sacket’s Harbor), 72 to 1,046 at midwater (5-45 m), and 0 to 44 in the deepest samples (91-220 m). Counts for surface and midwater samples were highest (642 to 2,516 cells/ml) at inshore stations (1.2 to 5 miles off shore) off Toronto, along the south shore, and up the eastern shore to the North Channel. Abundance of phytoplankton was highest in the Toronto-Hamilton area on the western shore and near the mouth of the Chaumont and Black River Bays at the eastern end of the lake. The remaining areas of the north shore and most of the central portions of the lake had low densities of phytoplankton. Although numbers of phytoplankton were greatest at the surface at most stations, numbers were also appreciable at mid- depth. Numbers at mid-depth were greater than those at the surface at four stations (35, 38, 74, and 78).

Major Groups of Phytoplankton

The dominant plankters were green algae, followed by diatoms. These two groups were present in surface and midwater samples at all stations (Table 4). Green algae were 2-5 times as abundant as diatoms in nine surface samples. In midwater samples green algae were 2-9 times as abundant as diatoms at seven stations. Although diatoms were more abundant than green algae in two surface and six midwater samples, abundance of diatoms never exceeded 1.7 times that of the green algae. Blue- Table 1. Phytoplankton counts (cells/ml) [AH samples taken at surface; station locations given in Fig. 1;

Taxon 4 7 11 17 18 28 32

Chlorophyceae Ankistrodesmus convolutus Corda 4 - 4 9 5 - - A. falcatus (Corda) Ralfs 4 2 4 21 24 2 7 Closteriopsis longissima Lemmermann - - - 4 - - Coelastrum cambricum Archer ------C. microporum Naegeli 24 26 859 135 14 23 32 Cosmarium sp. Corda - - 2 2 2 4 Oocystis spp. Naegeli 67 65 148 126 65 65 148 Pediastrum duplex Meyen 72 - - 56 12 - 42 P. simplex var duodenarium (Bailey) Rabenhorst 18 - 56 35 82 30 - Scenedesmus bijuga (Turn.) Lagerheim 51 33 102 67 59 67 51 S. quadricauda IT&p:) de &&b&son 32 - 7 4 - 5 Schroederia Judayi G. M. Smith 2 - 7 10 4 5 - Sphaerocystis Schroeteri Chodat 68 37 183 111 196 86 179 Staurastrum sp. Meyen - - 28 5 9 2 - Tetraedron minimum (A. Braun) Hansgirg 2 - 7 9 5 - 2 Unidentified filament - - 84 30 9 - Others2 - -~- 4 -- 49 2 Total Chlorophyceae 344 163 1,400 674 511 340 482 Bacillariophyceae Centrics 172 35 228 32 76 95 179 Pennates 67 68 +$ 23 107 90 58 Total Baciilariophyceae 239 103 255 183 185 237 Myxophyceae Anabaena flos-aquae (Lyngb.) de Brdbisson 26 14 - 98 54 - Aphanizomenon flos-squae (L.) Ralfs 82 12 - 2 95 21 - Gomphosphaeria lacustris Chodat ------Total Myxophyceae 108 26 - - 100 149 21

Dinophyceae Ceratium hirundinella (O.F.M.) Schrank - - 4 5 2 - Peridinium sp. (Ehrenberg) Stein ---7 i - -72- --- Total Dinophyceae 7 11 4 2 - Euglenophyceae 58 9 70 93 184 154 128 Chrysophyceae Dinobryon sp. Ehrenberg -I----- ___---- - 4 - Total Phytoplankton 751 308 1,755 1,026 985 834 868 i Two surface samples were collected at station 85. 2 Closterium sp. Nitzsch, Crucegenia quadrata Morren, Dictyosphaerium ehrenbergianum Naegeli, Dimorphococcus lunatus A. Braun, from Lake Ontario, September 1964

dash indicates organism was not encountered in the sample.]

Station number 33 35 38 40 45 50 55 59 65 71 74 78 81 '85 '85 99

- - 4 5- 5274- 9 4 4 2 - - 9 - 4 4 7 5 10 12 18 18 2 4 12 - - - 5-----2-- 4 2 5 ------121 176 70 119 - 7 12 24 32 7 30 70 88 46 46 33 95 77 44 70 65 2 - 4- 2 - - 2 ---- 2 - 53 53 47 49 46 54 33 105 96 84 39 76 53 60 82 65 9 - 2 - 81 - 28 91 10 91 76 4 58 30 -

33 - - 37 14 63 - 12 10 23 61 33 77 32 28 14 74 26 26 24 35 21 12 56 56 60 54 126 123 24 35 28 - -10 - - - 7----- 18 ------12 2 ------56 153 ------26 23 14 24 9 7 9 22525774222- 4 4 -

5- - - 4 12 - - 4 4 5 12 4 18 - - 49 - 9 ------234 273 116 AL 281427,74-.-- i?% 528 339 399 206

112 23 111 114 65 46 32 144 198 60 191 100 123 70 102 142 61 46 --53 135 26 39 102 54 - 35 ---5 58 90 372 77 91 53 173 69 164 249 91 85 134 198 233 65 249 190 495 147 193 195

100 37 7 - - 10 111 - 10 40 - 116 664 133 ------149 63 35 14 - 622 19 - 82 - - - - - _ ------204 32 - - - 58 14 100 -E--T- -10 315 181 73 75 14 174 1,300 19 133 82

- - - - _ 2 - - 2 - 4 2 7 4 - - - - 4 ------2 2 2 4 21 - - - - 4 - 2 - - 42 667 4-T

79 2 5 28 - - - 98 123 72 61 21 165 18 77

2 2 - - - _ ------588 383 232 443 257 378 637 786 843 485 642 964 2,516 505 747 560 Table 2. Phytoplankton counts (cells/ml) [Samples taken at mid-depths (5-45 m); station locations given in Fig. 1;

Taxon 17 (:l, (1:) (l’s, (:i) (9) (E) (Z) (ig, Chlorophyceae Ankistrodesmus convolutus Corda 2 A. falcatus (Corda) Ralfs 7 9 4 Closteriopsis longissima Lemmermann 2 Coelastrum microporum Naegeli 7 19 93 119 23 Cosmarium sp. Corda 2 2 2 Lagerheimia ciliata (Lag.) Chodat 2 9 2 2 Ooc@is spp. Naegeli 33 28 10 128 33 74 14 16 Pediastrum duplex Meyen 116 46 96 7 P. simplex var. duodenarium (Bailey) Rabenhorst 40 37 193 Scenedesmus bijuga (Turp.) Lagerheim 56 46 35 10 65 5 7 S. quadricauda (Turp.) de Brcbisson 4 7 18 14 Sphaerocystis Schroeteri Chodat 86 2 37 51 102 Staurastrum sp. Meyen 2 2 2 2 2 Tetraedron minimum (A. Braun) Hansgirg 4 2 2 2 Unidentified filament 4 18 Others ’ Total Chlorophyceae 233 259 58 328 151 353 172 218

Bacillariophyceae Centrics 77 63 7 72 79 195 107 146 Per-mates 63 46 5 --144 148 256 67 220 Total Bacillariophyceae 140 109 12 216 227 451 174 366

Myxophyceae Anabaena flos-aquae (Lyngb.) de Brebisson 54 42 Aphanizomenon flos-aquae (L.) Ralfs 24 Unidentified filament -I.- -- L Total Myxophyceae 54 42 24

Euglenophyceae 28 33 7 16 137 93

Others z 2 2 2 - Total phytoplankton 457 443 72 551 394 941 465 584 1 Closterium sp. Nitzsch, Coelastrum cambricum Archer, Schroederia Judayi G. M. Smith. 2 Dinobryon sp. Ehrenberg, Ceratium hirundinella (O.F.M.) Schrank Peridinium sp. (Ehrenberg) Stein. from Lake Ontario, September 1964 dash indicates organism was not encountered in the sample.]

4 4 2 4 5 2 4 7- - 2 9 4

2 - 2- - - 2 - 2 56 60 40 4 5 4 12 7 7 104 105 14 2 7 2 2 - 2 - 4 2 2 2 - - - - 8 58 61 51 37 2 9 - 14 9 84 26 14 23 19 53 - 28 - 146 142 112 19 - 14 28 26 44 - 28 40 142 35

74 24 21 19 14 7- - - 96 105 23 14 16 4 - 4 - - 7 8 146 23 - - - - 14 - 2 4 - 2 - 7 4 5 4 4 2

4 2 2 4 2 - 4 9 2 42 26 174 12 31- - - - 37 -----2 2 -----__2- -- - 134 --158 218 350 183 270 65 134 47 84 66 619 535 45 366 88

116 19 167 33 72 10 5 16 42 167 153 35 72 8 ---93 74 74 --42 33 5 21 37 24 49 246 23 133 10 209 93 241 75 105 15 26 53 66 216 399 58 205 18

86 - - - - 5 -

- - 12 100 209 ------2 86 - - - - 17 102 209

51 181 72 - - - - 139 10 60

5 2 - - - 7 - 2 --- --__~ 483 626 582 345 170 149 73 137 132 998 1,046 103 842 m Table 3. Phytoplankton counts (cells/ml) from Lake Ontario, September 1964 [Samples taken just above the bottom; station locations given in Fig. 1; dash indicates organism was not encountered in the sample.]

Station number and (in parentheses) depth in meters Taxon 7 17 28 33 38 65 71 (100) (91) (142) (91) (97) (220) (178) Chlorophyceae Coelastrum microporum (Naegeli) 2 ---- Bacillariophyceae Centrics 2 2 - 28 40 14 28 Pennates 4 5 9 10 4 - 4 Total Baccilariophyceae 2 1 s 38 44 i3 3-i Total phytoplankton 6 7 11 38 44 14 32

Species

None of the genera or species of phytoplankton were confined to any one section of the lake. Three forms (Scenedesmus bijuga, Oocystis spp., and Coelastrum microporum) occurred at all stations, either at the surface, at mid-depth, or both. Organisms at 75% of the stations were Ankistrodesmus falcatus, Pediastrum duplex, P. simplex var. duodenarium, Sphaerocystis Schroeteri, Tetraedron minimum, Cosmarium, Staurastrum, and members of the Euglenophyceae. Diatoms were found at all stations (for a list of the species see Reinwand, 1969). The trophic nature of Lake Ontario cannot be described sim- PlY. According to Beeton (1965) Lake Ontario is a mesotrophic lake, with the biota of oligotrophy and the physicochemical characteristics of eutrophy. Its chemical content is understandably similar to that of Lake Erie, since Lake Erie water moves from west to east, eventually entering Lake Ontario through the Niagara River. Thus, the chemical content which in turn affects the trophic nature of Lake Ontario, is influenced in large measure by the chemical conditions in Lake Erie. The composition of phytoplankton in Lakes Erie and Ontario was similar. Both lakes are dominated by diatoms for most of the year, but green and blue-green algae often become dominant during the summer (Nalewajko, 1966; Tucker, 1949; Schenk and Thompson, 1965; Davis, 1962, Burkholder, 1960). The mid-september sampling period of this study showed that the Chlorophyceae were most important. Table 4. Number of cells/ml of various phytoplankton at the surface and mid-depths of Lake Ontario, September 1964

Station Depth Chloro- Bacillario- Myxo- Total (meters) phyceae phyceae phyceae phytoplankton 4 0 344 239 108 751 11 233 140 54 475 7 0 163 103 26 308 18 58 12 0 72 11 0 1,400 274 0 1,755 18 328 216 0 551 17 0 674 255 0 1,026 9 151 227 0 394 18 0 511 183 100 985 11 353 451 0 941 28 0 340 185 149 834 12 172 174 24 465 32 0 482 237 21 868 16 218 366 0 584 33 0 234 173 100 588 15 218 209 0 483 35 0 273 69 37 383 15 350 93 0 626 38 0 116 164 7 292 12 183 241 86 582 40 0 162 249 0 443 18 270 75 0 345 45 0 166 91 0 257 38 65 105 0 170 50 0 281 85 10 378 18 134 15 0 149 55 0 188 134 315 637 30 47 26 0 73 59 0 309 198 181 786 65 0 410 233 73 843 30 84 53 0 137 71 0 271 65 75 485 25 66 66 0 132 74 0 312 249 14 642 10 619 216 17 998 78 0 573 190 174 964 18 535 399 102 1,046 81 0 528 495 1,300 2,516 85 0 369 170 76 626 31 45 58 0 103 91 5 366 205 209 842 99 0 206 195 82 560 45 88 18 0 106

35 Table 5. Comparison of high phytoplankton counts (cells/ml) and abundance of certain water-quality-related benthos (number/mz) at selected inshore stations

Bottom fauna 1 Total phytoplankton Saprophobes Saprophile Station Surface 5-45 meters Stylodrilus Pontoporeia Tubifex heringianus 2 affinis 3 tubifex4 4 751 457 254 0160 11 1,755 551 92 2,041 0 17 1,026 394 0 5794 18 5985 5941 869 3,380 0 32 868 584 1,630 00 59 786 0 00 665 843 137 27 00 74 964 1,046 0 675 0 81 2,516 11 00 91 842 583 729 0

1 Data from Hiltunen (1969). 2Range at other stations: 583 to 4,790; median 1,183. 3Range at other stations: 383 to 9,968; median 1,674. 4Range at other stations: 0 to 54. 5 Deep water; high phytoplankton counts may be due to currents. 6Station about 15 miles offshore.

Although the phytoplankton of Lake Ontario was qualitatively similar to that of Lake Erie, it was quantitatively more similar to Lake Michigan. That Lake Ontario has not progressed to the same level of eutrophy as Lake Erie may be due to the large volume of deep water in its basin (Beeton, 1965), and in this re- spect Lake Ontario may be considered trophically similar to Lake Michigan. A study of Lake Michigan by Stoermer and Kopczynska (1967) revealed that total phytoplankton counts on August 7, 1962, ranged from 215 to 1,387 cells/ml. These figures fell within the range observed in Lake Ontario in September 1964. Similarly, data presented by Damann (1966) for average monthly counts at water plants in Chicago in 1928-45 and Milwaukee in 1940-63 fell within the range of counts in Lake Ontario. Stoermer and Kopczynska (1967) and Damann (1945) found that diatoms were dominant in Lake Michigan, but unlike Lake Ontario, green and blue-green algae were relatively unimportant. The occurrence of the majority of the highest total phytoplankton counts (greater than 700 cells/ml) close to shore, especially near heavily populated areas (stations 4, 11, 17, 59, 78, and 81) suggests that these high densities may be the result of enrichment. This view finds support from data on the bottom fauna (Hiltunen, 1969) in these areas which was characterized by relatively large numbers of the pollution-tolerant Tubifex tubifex and by the absence or low numbers of the pollution-intolerant Stylodrilus heringianus and Pontoporeia affinis (Table 5). Although the large numbers of phytoplankton close to shore conceivably might be due to currents or perhaps to warmer water, the presence of a saprophile and the absence of saprophobes in the bottom fauna in these areas suggest that enrichment offers the better explanation.

Literature Cited

BEETON, ALFRED M. 1965. Eutrophication of the St. Lawrence Great Lakes. Limnol. Oceanogr. 10:240-254. BURKHOLDER, PAUL R. 1960. A survey of the microplankton of Lake Erie. In; Limnologi- cal Survey of Eastern and Central Lake Erie, 1928-1929. U.S. Fish and Wildl. Serv., Spec, Sci. Rept., Fish. 334:123-144. DAMANN, KENNETH E. 1945. Plankton studies of Lake Michigan. I. Seventeen years of plankton data collected at Chicago, Illinois. Amer. Midland Naturalist, 34:769-796. 1966. Plankton studies of Lake Michigan. III. Seasonal periodicity of total plankton. Univ. Michigan, Great Lakes Res. Div., Pub. No. 15, p. 9-17. DAVIS, CHARLES C. 1962. The plankton of the Cleveland Harbor area of Lake Erie in 1956-1957. Ecological Monographs, 32:209-247. 1966. Plankton studies in the largest great lakes of the world with special reference to the St. Lawrence Great Lakes of North America. Univ. Michigan, Great Lakes Res. Div., Pub. No. 14, p. l-35. HILTUNEN, JARL K. 1969. The benthic macrofauna of Lake Ontario. Great Lakes Fish. Comm., Tech. Rept. No. 14. p. 39-50. McCOMBIE, A. M. 1967. A recent study of the phytoplankton of the Bay of Quinte, 1963-1964. Proceed., Tenth Conf. Great Lakes Research, p. 37-62. NALEWAJKO, C. 1966. Composition of phytoplankton in surface waters of Lake On- tario. J. Fish Res. Bd. Canada, 23:1715-1725. 1967. Phytoplankton distribution in Lake Ontario. Proceed., Tenth Conf. Great Lakes Research, p. 63-69. REINWAND, JERRY F. 1969. Planktonic diatoms of Lake Ontario. Great Lakes Fish. Comm., Tech. Rept. No. 14. p. 19-26. SCHENK, C. F. and R. E. THOMPSON. 1965. Long-term changes in water chemistry and abundance of plankton at a single sampling location in Lake Ontario. Univ. Michigan, Great Lakes Res. Div., Pub. 13. p. 197-3ca STOERMER, E. F. and E. KOPCZYNSKA. 1967. Phytoplankton populations in the extreme southern basin of Lake Michigan, 1962-1963. In: Proc. Tenth Conf. Great Lakes Res., Int, Assoc. Great Lakes Res., pp. 88-106. TUCKER, ALLAN. 1948. The phytoplankton of the Bay of Quinte. Trans. Am. Microsc. Soc., LXVII:365-383. THE BENTHIC MACROFAUNA OF LAKE ONTARIO’

Jarl K. Hiltunen U.S. Bureau of Commercial Fisheries Biological Laboratory Ann Arbor, Michigan

ABSTRACT The presence and relative abundance of bottom macrofauna in Lake Ontario are documented, Bottom samples were collected at 24 stations in September 1964. The quantity of organisms and the distribution of some species were affected by depth of water. Samples from the shal- lower stations (47.5 m or less) yielded an average of 41,631 organisms per m2 whereas the deeper stations (91.5 m or more) yielded an average of only 7,938. The Oligochaeta, the most abundant group of macroinver- tebrates, was represented by four families - Enchytraeidae, Lumbriculidae, Naididae, and Tubificidae. The lumbriculid worm, Stylodrilus heringianus, and the burrowing amphipod, Pontoporeia affinis, were rare or absent in areas affected by pollution. In kinds and abundance of organisms, the bottom fauna in Lake Ontario was generally similar to that in Lake Michigan.

Introduction

The only early published data on the bottom fauna of Lake Ontario are the reports of Nicholson (1872 and 1873) and Adam- stone (1924), which are brief and deal only with fauna from the western end of the lake. Occasional taxonomic monographs have recorded certain species from the lake, but none of them give a lakewide treatment of the macrobenthos. Consequently, no quali- tative or quantitative comparisons can be made between past and present records.

Methods and Materials

Bottom samples for benthos were collected at 24 stations (Fig. 1), which were selected to provide broad and representative 1 Contribution No. 389 of the Ann Arbor Biological Laboratory, U.S. coverage of the lake. Three samples were taken at each station (except where otherwise indicated in Table 1) with a 1/16 m2 Smith-McIntyre dredge, and washed through a U.S. Standard NO. 30 wire mesh screen (about 0.5-mm mesh). The residue was preserved in formalin and the organisms were later sorted under magnification of 15 diameters. The present work includes primarily those organisms which were in or on the bottom sediment and which were retained in the residue after the samples were screened. Although hydras were found at a few stations, they are not included here because most were undoubtedly lost or destroyed when the samples were sieved. Occasionally some planktonic cladocerans (including Leptodora kindtii Focke), calanoid copepods, and Mysis relicta were observed but they were most likely trapped in the dredge as it was lowered to the bottom. The presence of several Mysis relicta, however, justified inclusion of this form in Table 1. When possible, the organisms were identified to species. The classification of various groups is according to several current authorities. The nomenclature of the Oligochaeta follows Brink- hurst (1964, 1965) and Brinkhurst and Cook (1966). Over 7,800 oligochaetes were individually examined under microscopic magnification of 35X or more. Their identification to species was based on external or internal organs. The one lumbriculid species, Stylodrilus heringianus, and the Naididae were identified by the configuration of their chaetae. Some tubificid species were determined by the shape of their somatic chaetae (which does not change with maturity) and others were recognized by organs evident only at sexual maturity. Those identified solely by their chaetae were: Aulodrilus, Peloscolex, Rhyacodrilus, and Limnodri- lus udekemianus, Potamothrix vejdovskyi, Psammoryctides curvisetosus, and Tubifex ignotus. Those identified by anatomical fea- tures evident at sexual maturity were: Limnodrilus cervix, L. hoffmeisteri, L. profundicola, Potamothrix moldaviensis, Tubifex kessleri americanus, and T. tubifex. The abundance of species in the latter group was underestimated because only the sexually mature individuals could be positively identified. Specimens that were sexually immature and could not be identified by other means were categorized as “unidentifiable immature with capilliform chaetae” and “unidentifiable immature without capilliform chaetae” (Table 1). The immature forms of Potamothrix bavaricus, Tubi- fex kessleri americanus, and T. tubifex, compose the group with capilliform chaetae, but the first two species were rare. The second category is composed of immature forms of all other species. Valvata sincera and V. tricarinata include all forms which have shell characteristics that most nearly fit each respective species. No attempt was made to separate the shell forms which Table 1. Number of organisms per Square meter [Depth in meters

Platyhelminthes Neorhabdocoela Tricladida Nemata Annelida Hirudinea Glossiphoniidae Helobdella stagnalis (Linnaeus) Piscicolidae Oligochaeta Enchytraeidae Lumbriculidae Stylodrilus heringianus Claparede Naididae Arcteomis lomondi (Martin) Chaetogaster diaphanus (Gruithuisen) Nais SP. Ophidomis serpentine (Müller) . . . Piguetiella michiganensis Hiltunen Slavina appendiculata (d’Udekem) Vejdovskyella intermedia (Bretscher) Tubificidae Aulodrilus americanus Brinkhurst and Cook A. limnobius Bretscher A. pigueti Kowalewski A pluriseta (Piguet) Limnodrilus cervix Brinkhurst . . . L. hoffmeisteri Claparede L. profundicola (Verrill) L. udekemianus Claparede Peloscolex ferox (Eisen) P. multisetosus (Smith)3 P. variegatus Leidy Potamothrix bavaricus (Oschmann) P. moldaviensis Vejdovsky and Mrazek P. vejdovskyi (Hrabe) Psammoryctides curvisetosus Brinkhurst and Cook Rhyacodrilus coccineus (Vejdovsky) R montanus (Brinkhurst) Rhyacodrilus SP. Tubifex ignotus (Stolc) T. kessleri americanus Brinkburst and Cook T. tubifex (Müller) Unidentifiable immature With capilliform chaetae Without capilliform chaetae Polychaeta Manayunkia speciosa Leidy Arthropoda Arachnoidea Hydracarina

1 Abundance of oligochaetes based upon only one grab. Chaetogaster diaphanus was present in samples not examined. 2All values are based upon only one incomplete grab. %cludes the less common subspecies longidentus Brinkhurst and Cook, 4Species determined as Unionicola crassipes @Ii&r) by David R. Cook. at various sampling stations in Lake Ontario, 1964 in parentheses]

59 11 ...... 81 77 ...... 86 5 16 11 . . . 124 ._. . . . 5 11 ...... 11 92 86 405 270 972 362 891 42 42 151 38 160 42 . . . 5 ...... 22 5 . . . 5 ...... 108 77 ...... 11 ...... , , . . , . . . . . 5 ...... 194 ... 5 ... 65 ......

11 ... 583 686 1,183 1,863 2,106 237 42 869 1,237 799 864 32 27 ...... 5 ...... * ...... , ...... , ...... * ...... , ... . . , ...... 22 ......

... 70 ...... 11 ...... 27 983 ...... 16 22 38 32 108 42 11 11 38 5 178 38 ...... 11 11 ...... 966 156 2,057 215 589 ... 5 ...... 5 ...... 11 ...... 11 11 ...... 16 ...... 16 ...... 38 11 ...... 448 ...... , ... 27 156 ...... 540 ...... 11 ...... 335 5 ... 5 ...... 27 22 ...... 5 . . 54 ... 16 ...... 5 ... 5 27 . . . 97 124 . . . 49 259 65 92 . . . 42 145 140 113 27 243 4541,145 16 464 11 27 38 11 32 27 383 178

804 49 16 ......

... 45 16 11 . . . 5 ...... Table 1.

Organism 74 4 11 117 32 40 50 59 78 (11) (13.5) (18.5) (18.5) (18.5) (18.5) (18.5) (18.5) (18.5) Crustacea Ampbipoda Gammarus SP.~ 1,199 189 . . . 891 . . . 22 1,350 232 Pontoporeia affinis Lindstrom 675 . . . 2,041 ._. 8,288 4,217 . . . 1,064 Isopoda Asellus comnumis RacovitzaG ...... 233 . . . 49 . . . 5 327 . Mysidacea Mysis relicta Loven ...... Ostracoda 11 16 281 . . . 77 70 54 . . Insecta Diptera Ceratopogonidae (=Heleidae) ...... 5 Chironomidae (=Tendipedidae) Chironomus spp.7 ...... 16 ...... 118 Cryptochironomus cf. abor- tims Malloch ...... 5 C. cf. camptolabis Kieffer . . . 5 . . ... 38 ...... C. cf. digitatus Kieffer 11 ...... 22 ... 54 C. cf. mis (Townes) ...... 5 . . * ...... 5 c. cf. vdneratus (Zetter- sted)8 ...... 5 . . . Heterotrissocladius Spp. . . . 5 81 27 ‘&I 38 ::: 38 Micropsectra sp. 49 . . . 77 70 313 ...... 184 Microtendipes. sp. 5 ...... 11 11 . . . 22 Paralauterborniella Sp...... 5 ...... Polypedilum cf. fallax (Johannsen) . , ...... 11 ...... Potthastia cf. Z0ngima?Ia Kieffer 5 . . . , ...... 11 . . . 16 Procladius spp. . 38 156 178 16 5 27 140 200 Pordiamesa cf. bathyphila Kieffer ...... 5 42 . . . Stictochironomus Sp...... Trichoptera Oecetis Sp...... Mollusca Gastropoda Amnicola binneyana Hannibal ...... 11 ...... A. limosa Say ...... 718 A. lustrica Pilsbry ...... 5 ...... Amnicola spp. 561 ...... Bulimus tentaculatus (Linnaeus) ...... 11 ...... Lymnaea emarginata say ...... 49 5 27 Physa sp. 11 . . . 5 5 . .. 32 5 5 Valvata sincera Say [sensu lato] 680 5 16 . . . 86 5 184 65 556 v. tricarinata (Say) [ SSIlS” 1ato] ...... 49 11 5 ...... Pelecypoda Pisidium SPP. 1,889 3,941 2,440 1,733 2,122 2,554 6,188 8,477 3,062 Sphaerium corneum (Linnaeus) . . . 685 65 351 11 1,080 1,371 27 S. (Musculium) lacustre jayense Prime . . . 11 ...... 5 . . S. nitidum Clessin ...... 59 11 189 . . . 297 . . . . S. simile (Say) . . 5 ...... S. striatinum (Lamarck) ...... 145 . . . 49 5 . . . s. (M.) transversum (Say) 38 167 . . . . 49 ......

5 Probably G. fasciatus Say. 6 Pending taxonomic revision by W. D. Williams. 7Subgenera Limnochironomus and Chironomus sympatric at some stations. 8Cf. species “a” of Curry (1958). (Continued)

1,787 740 729 22 16 ...... 27 38 729 3,866 7,970 8,186 9,968 432 1,010 3,380 940 1,750 1,674 383 453

1,912 1,345 1,053 561 5 . . 5 ......

...... 5 11 5 5 ...... 42 . . . 599 81 124 . . . 27 308 .., 113 11 97 151 11 22

......

16 1,403 ... 11 27 ......

...... 11 ...... , ......

...... , , ...... 11 ...... 5 324 81 308 173 248 302 189 49 124 156 2,268 394 329 ... 22 ...... * ...... 16 ......

...... 38 173 65 11 42 ...... 5 . 5 ......

5......

...... , ...... , ...... 200 ......

108 ...... 5 11 ... 11 81 ...... 5 5 ...... * ...... 421 302 259 11 38 5 ...... 86 59 ...... 616 1,328 2,171 1,539 2,224 3,434 3,958 211 151 556 437 194 637 97 16 42 146 275 146 454 11 ......

...... 108 ...... 5 ...... varied from the typical shape and are sometimes given individual taxonomic status. The species of Pisidium are difficult to identify and, except for P. conventus, I consider them here only by genus. The stations listed in Table 1 are ranked according to depth from 11 to 225 m. Because the maximum habitat depth for many species is between 47.5 and 91.5 m, the stations were separated into two depth zones -“shallow” (47.5 m or less) and “deep” (91.5 m or more). These arbitrary zones are not intended to corre- spond to any conventional littoral and profundal zones of lake depth.

Ecology and Abundance

The distribution and abundance of benthos in a body of water depend on a number of environmental factors, but the limited data of this work allow only observations on the influence of depth and water quality on some species. Bottom organisms were far more abundant in shallow than in deep water. The average number of organisms per m2 was 41,631 in the shallow zone and 7,938 in the deep zone.

Oligochaeta Oligochaeta was the largest group of macrobenthos found in Lake Ontario. The class was represented by four families- Enchytraeidae, Lumbriculidae, Naididae, and Tubificidae. Enchy- traeids (identified here only to family) were widespread, exhibited no distinct depth preference, and apparently were never abundant. Stylodrilus heringianus (Lumbriculidae) was apparently common throughout the lake except in a few places where the environment may have been unfavorable. Pollution may have caused the absence of this species at station 17 off Toronto, Ontario, and station 59 off Rochester, New York, and reduced its numbers at station 81. Its absence from stations 74 and 87 is inexplicable. Johnson and Matheson (1968) also found the species in western Lake Ontario but not in Hamilton Bay where the waters were con- taminated by pollutants. The term “sludge worm,” by which aquatic oligochaetes are frequently known, cannot be applied to S. heringianus. Seven species of Naididae were taken, all from the shallow zone. None were abundant, but many were probably lost when the samples were sieved. Among the naidids, Vejdovskyella intermedia attained the greatest depth (47.5 m). The family Tubificidae contributed the largest number of species (21) and individuals. Limnodrilus hoffmeisteri was the most common and widespread species; if a large proportion of the forms that were “unidentifiable immature without capilliform chaetae” are assumed to be this species, L. hoffmeisteri would have composed most of the total tubificids at productive stations 4, 17, and 59. The common species - Potamothrix moldaviensis, P. vejdovskyi, Peloscolex ferox, and P. multisetosus - were found in the shallow zone, as were the less common Aulodrilus americanus, A. pluriseta, Limnodrilus udekemianus, and Tubifex ignotus. Limnodrilus cervix is nearly saprobiontic and its distribution was probably influenced more by water quality than by depth. Habitat preferences of the rare species, Aulodrilus limnobius, A. pigueti, Potamothrix bavaricus, Psammoryctides curvisetosus, Rhyacodri- lus coccineus, and R. montanus, are not fully known but they apparently do not have a wide depth distribution. Limnodrilus Pro- fundicola and Tubifex kessleri americanus were found only at the the two deepest stations (183 and 225 m). The location of L. PYO- fundicola is in sharp contrast to that reported by Johnson and Matheson (1968) who found the species only in Hamilton Bay. I have yet to find L. profundicola in a polluted habitat in the Great Lakes. Peloscoiex variegatus and Rhyacodrilus sp. were collected in both depth zones but may prefer depths between 35 and 195 m. Tubifex tubifex showed no depth preferences. Since the species is known to inhabit organically polluted areas, its high abundance at station 17 near Toronto was not unexpected. Most, if not all, of the specimens that were “unidentifiable immature with capilliform chaetae” were probably T. tubifex. The species is clearly facultative toward water quality. Not only did it thrive in an area of urban pollution, but it also was in deep water where the substrate was presumed to be comparatively nutrient poor. Potamothrix vejdovskyi was ordinarily abundant in the productive areas (i.e., stations 4 and 59) but it was poorly represented at productive station 17. Competition with the large numbers of other tubificids may have caused the low abundance of P. vejdovskyi at station 17. The species composition of oligochaetes at station 4 is para- doxical and difficult to explain. The saprophilous species, Limno- drilus cervix, L. hoffmeisteri, Peloscoiex multisetosus, and Tubi- fex tubifex, coexist with saprophobic Stylodrilus heringianus. The Niagara River may deliver sufficient nutrients to support large numbers of the saporphiles but, on the other hand, the river must also be sufficiently free of elements which could inhibit S. heringianus. The presence of large numbers of the uncommon Tubifex ignotus at this station resembles its distribution in Lake Michi- gan where it was also abundant only near a river mouth (Hiltunen, 1967). Nicholson (1873) recorded some oligochaetes in Lake Ontario as “Saenuris canadensis,” “Saenuris sp.,” and “Lumbriculus sp.,” but his descriptions are inadequate and the taxonomy of these early names is so obscure that none can be reliably related to current oligochaete classification. His Lumbriculus sp. may have been Stylodrilus heringianus. Adamstone (1924) recorded only the group Oliogochaeta.

Amphipoda The abundance of Pontoporeia affinis in the shallow zone was apparently reduced by pollution or by excessive competition with organisms that thrive in a polluted environment. The species was rare or absent from stations near areas of urban contamination, e.g., stations 4 and 59 (Table 1). The current from the Niagara River may have affected its abundance at station 4. The scarcity of P. affinis at stations 81 and 87 may have been due to pollution from the Black River at station 81 (near Sackets Harbor) and low dissolved oxygen in the hypolimnion at station 87. Depth should not have been limiting since the species was taken at station 74, which was the shallowest (11 m) station sampled. The absence of P. affinis at station 32 is unexplained. Although data on depth distribution are scanty, P. affinis appeared to be more abundant in the shallow zone (3,621 individuals per m”) than in the deep zone (1,252 individuals per m”). If the stations affected by pollution were omitted from the analysis, the average numbers in the shallow zone would have been even high- The general irregularity of abundance of P. affinis resem- %d that found by Marzolf (1965) in Lake Michigan. Two sizes or age groups-5 mm and less, and 7-8 mm (measured in length from base of antennae to the extremity of terminal uropod) - were found at some stations, but no relationship appeared between size of individuals and depth of water, except that the smallest (1 mm) were collected only in the deep area. The effect of environmental conditions on Gammarus was not apparent. Gammarus was abundant off Rochester but absent off Toronto. This amphipod crustacean was limited to depths of less than 33 m.

Others The influence of depth was reflected in the populations of Chironomidae (Table 1). Except Heterotrissocladius and PYO- clad&, the genera were not found at stations deeper than 47.5 m. The presence of Procladius at the more profundal stations 5 and 18 was in contrast to the observation of Brinkhurst, Hamilton, and Herrington (1968) who reported the group only from near shore. Manayunkia speciosa, Asellus communis, most midgefly larvae, Oecetis sp., and all gastropods were restricted to the shallow zone. All of the Pisidium from the deep zone were P. conventus, which has been found throughout the Great Lakes (Heard, 1962; Henson, 1966; Herrington, 1962) and ordinarily at depths greater than 15 m. The various species of Sphaerium inhabited only the shallow zone (S. corneum was most common). The profundal bottom macrofauna of Lake Ontario was similar to that of Lakes Michigan and Huron. The abundance of sphaeriid clams, oligochaetes, and Pontoporeia affinis, was nearly alike in Lakes Michigan and Ontario but in Lake Huron the relative abundance of these organisms (Teter, 1960; Schuytema and Powers, 1966) was considerably less than in the other two lakes.

Acknowledgments

I thank E. G. Berry for his assistance in the identification of some of the Gastropoda, H. B. Herrington for his assistance in the identification of some of the Sphaeriidae, D. R. Oliver for his confirmation of the identity of some of the Chironomidae, and W. D. Williams for his advice on the taxonomy of Asellus.

Literature Cited

ADAMSTONE, F. B. 1924. The distribution and economic importance of the bottom fauna of Lake Nipigon with an appendix on the bottom fauna of Lake Ontario. Univ. Toronto Studies, Biol, Series, 25:35-100, Pub. Ont. Fish. Res. Lab., No. 24. BRINKHURST, RALPH 0. 1964. Studies on the North American aquatic Oligochaeta. I. Naididae and Opistocystidae. Proc. Acad. Nat. Sci. Phila., 116(5):195- 230. 1965. Studies on the North American aquatic Oligochaeta. II. Tubi- ficidae. Proc. Acad. Nat. Sci. Phila., 117(4):117-172. BRINKHURST, RALPH 0. and DAVID G. COOK. 1966. Studies on the North American aquatic Oligochaeta. III. Lum- briculidae and additional notes and records of other families. Proc. Acad. Nat. Sci. Phila., 118(1):1-33. BRINKHURST, RALPH O., A. L. HAMILTON, and H. B. HERRINGTON. 1968. Components of the bottom fauna of the St. Lawrence Great Lakes. Univ. Toronto, Great Lakes Inst. Publ. No. PR 33, 50 p. HEARD, WILLIAM H. 1962. The Sphaeriidae (Mollusca: Pelecypoda) of the North American Great Lakes. Am. Midl. Nat., 67(1):194-198. HENSON, E. BENNETTE. 1966. A review of Great Lakes benthos research. Univ. Mich. Inst. Sci. and Tech., Great Lakes Res. Div., Pub, No, 14, pp. 37-54. HERRINGTON, H. B. 1962. A revision of the Sphaeriidae of North America (Mollusca: Pelecypoda). Univ. Mich. Mus. Zool., Misc. Pub. No. 118, 74 p.

49 HILTUNEN, JARL K. 1967. Some oligochaetes from southern Lake Michigan. Trans. Amer. Microsc. Soc., 86(4):433-454. JOHNSON, M. G. and D. H. MATHESON. 1968. Macroinvertebrate communities of the sediments of Hamilton Bay and adjacent Lake Ontario. Limnol. Oceanogr. 13(1):99- 111. MARZOLF, G. RICHARD. 1965. Substrate relations of the burrowing amphipod Pontoporeia affinis in Lake Michigan. Ecology 46(5):579-592. NICHOLSON, H. ALLEYNE. 1872. Preliminary report on dredgings in Lake Ontario. Am. Mag. Nat. Hist., Series 4, 10:276-285. 1873. Contribution to a fauna Canadensis; being an account of the animals dredged in Lake Ontario in 1872. Can. Jour. Sci. Lit, Hist., New Series, 13:490-506. SCHUYTEMA, GERALD S. and ROSS E. POWERS. 1966. The distribution of benthic fauna in Lake Huron. Univ. Mich., Inst. Sci, and Tech., Great Lakes Res. Div., Pub. 15, pp. 155- 163. TETER, HAROLD E. 1960. The bottom fauna of Lake Huron. Trans. Amer. Fish. Soc., 89(2):193-197. FISHERY SURVEY OF U.S. WATERS OF LAKE ONTARIO’

LaRue Wells U.S. Bureau of Commercial Fisheries Biological Laboratory Ann Arbor, Michigan

ABSTRACT

Gill nets and trawls were fished by the Bureau of Commercial Fish- eries R/V Cisco during September 19-23, 1964, at several locations and depths in the offshore United States waters of Lake Ontario. Water temperatures were low (3.7-8.3° C) at all fishing stations except one (16.4° C). Supplementary data were provided by the Bureau’s R/V Kaho in 1966. Alewives and smelt were common. Ciscoes were extremely scarce, but large; most of those caught were bloaters. Slimy sculpins were abundant, but no deepwater sculpins were caught. Yellow perch were scarce. Al- though the warm water species were inadequately sampled, trout-perch seemed to be abundant. Other species, all caught in small numbers, were lake trout, spottail shiners, burbot, threespine sticklebacks, and johnny darters from cold water and northern pike, lake chubs, white suckers, white bass, white perch, and rock bass from warm water.

Introduction

Fish populations of the U.S. waters of Lake Ontario are poorly described. The most comprehensive report is that of Stone (1947) who restricted his study to ciscoes taken from gill nets. The distribution and abundance of fish in Canadian waters of the lake are somewhat better documented, but no general information covering the offshore waters has been published since the work of Dymond et al. (1929). Pritchard (1931) discussed the abundance of ciscoes in Canadian waters of Lake Ontario. Commercial catch statistics indicate marked changes in fish populations in recent decades. Although the data for the present report are scanty and

‘Contribution No. 390 of the AM Arbor Biological Laboratory, U.S. Bureau of Commercial Fisheries. apply almost entirely to offshore U.S. waters, their publication here seems justified by the nearly total lack of information on the subject in the literature.

Methods and Materials

Experimental fishing gear consisted of bottom trawls and nylon gill nets. The trawl was semiballoon with a 39-foot headrope and a 1/2-inch mesh (extension measure) cod end. Trawls were towed for 10 minutes, along bottom contours, at about 3 mph. In seven of nine gill net sets the gangs included 150 feet each of 1-1/4- and 1-1/2-inch mesh (extension measure) and 300 feet each of the following mesh sizes (inches): 2, 2-3/8, 2-1/2, 2-3/4, 3, 3-1/2, and 4. In two sets the 1-1/4-, 2-3/8-, and 2-3/4-inch meshes were eliminated, and the length of the 1-1/2-inch mesh net was reduced to 50 feet. Seven of the gill net gangs were fished for one night and two for two nights. All fishing was conducted by the R/V Cisco off Oswego, Olcott, and Rochester, New York, during September 19-23, 1964. Additional information was provided by the Bureau of Commercial Fisheries R/V Kaho from trawl catches during November 1-15, 1966. The Kaho used a 52- foot headrope bottom trawl with a l-inch mesh cod end and made 30-minute tows at various depths in several locations in U.S. waters. The relatively large mesh of the cod end allowed the escape of most small fish. All references to southeastern Lake Michigan are from Wells (1968).

Water Temperature

Bottom water temperatures were low at all fishing locations except one. An upwelling was in progress along the south shore until the final day of fishing. Bottom temperatures ranged from 4.0 to 6.2° C in trawling areas, and 3.7 to 8.3° C at all gill net sets except at 3 fathoms off Olcott, where the temperature was 16.4° C (Tables 1 and 2). All catches but one, therefore, provide information primarily on the cold-water species.

Catches in Cold Water

Alewife (Alosa pseudoharengus) Alewives were taken in small to moderate numbers in most trawl tows, and in two gill net sets in cold water (Tables 1 and 2). They were most abundant in shallow water. All except one (1.7 inches long, total length) were older than 1 year. The range in length of the older fish was 5.2-7.8 inches (average, 6.5). Ale- wives were by far the most common species caught by the Kaho 52 Table 1. Number of fish of various species caught per lo-minute tow in Lake Ontario off Oswego (September 19) and Rochester (September 21), 1964

Location, depth (fathoms), and (in parentheses) bottom water temperatures (° C) Oswego Rochester Species ll0 a3 (5.1) (5.1) (Fo, (6.2) (PO) Alewife 2 102 42 2 1 - 2 165 174 1 38 1 Smelt (YOY) 552 25 5 1 242 26 58 - 1 - Smelt (adult) 14 266 305 12 1 - 5 12 121 2 50 6 Spottail shiner 10 - - - Burbot 1 - - Threespine stickleback 1 - - Trout-perch 780 2 - - Johnny darter 18 10 16 - 8 3 - Yellow perch 1 - Slimy sculpin 12 5 1,618 2,369 252 23 30 204 12 21 1 5-minute tow; catch figures adjusted to 10 minutes. 2 4-minute tow; catch figures adjusted to 10 minutes. Table 2. Number of fish of various species caught in gill nets set overnight (unless otherwise stated) in Lake Ontario off Oswego, Rochester, and Olcott, September 20-23, 1964

Location, depth (fathoms), and (in parentheses) bottom water temperature (° C) Oswego Rochester Olcott Species (23, (& 1 7 2 25 2 50 1 3 (4.7) (4.6) (3.9) (16.4) (2, Alewife 4 - 2 - 70 Lake herring 2 - Shortnose cisco 2 - Bloater 2 1 7 - Kiyi 1 Lake trout 1 Smelt (adult) 53 1 1 17 73 11 1 19 28 Northern pike 1 Lake chub 2 White sucker 15 White bass 2 White perch 6 Rock bass 9 - Yellow perch 5 - Slimy sculpin 1 7 15 1 1 Some mesh sizes eliminated or reduced. See text. 2 2-night set. in November 1966; catches in about 10 hours of trawling off Youngstown, Rochester, and Oswego, totaled 8,331 pounds (probably about 100,000 individuals). Greatest numbers were at 15 to 30 fathoms, but one large catch was made at 45 fathoms.

Ciscoes (Coregonus spp.) Ciscoes are evidently extremely scarce in Lake Ontario. None were taken in the trawls and only 15 in the gill nets. Most common among the ciscoes was the bloater (C. hoyi); nine were caught in the combined 50-fathom sets and one in the 25-fathom set off Rochester. Two shortnose ciscoes (C. reighardi), one kiyi (C. kiyi), and two lake herring (C. artedii) made up the re- mainder of the cisco catches. All of the ciscoes were large: bloaters averaged 11.2 inches (range, 10.1-12.0), shortnose ciscoes 12.2 inches, and lake herring 16.7 inches; the single kiyi was 12.1 inches long. The only cisco caught by the Kaho in 1966 was a large (2 pounds) lake herring. Ciscoes, particularly bloaters, were appreciably more abundant in U.S. waters of Lake On- tario in the 1940’s (Stone, 1947) than at present. In gill nets of three mesh sizes (2-3/8, 2-1/3, 2-3/4 inches) set at similar depths in 1942 and 1964, Stone took 52 ciscoes per thousand feet per lift (average set, 2 nights) as compared with only 1 in the present study. Stone’s catches almost certainly would have been larger if he had used nylon rather than cotton nets. The single cisco caught in all trawl tows in Lake Ontario contrasts marked- ly with catches of up to several hundred regularly caught in similar tows in southeastern Lake Michigan in 1964.

American smelt (Osmerus mordax) Smelt were relatively common in the catches. Young-of-the- year smelt were numerous in the trawl catches in shallow water, especially at 3 fathoms off Rochester and 10 fathoms off Oswego. Older smelt were caught in nearly every tow, and in all gill net lifts. Greatest numbers (over 100 per tow) in trawls were at 20 fathoms off Rochester and at 15 and 20 fathoms off Oswego. The average lengths of smelt in the trawls were 2.2 inches (range, 1.1-3.4) for the young fish and 6.1 inches (range 3.9-9.4) for the older ones. Smelt were nearly always the only fish besides alewives caught by the Kaho in November 1966; they were taken in 17 of 20 tows (up to 65 pounds per tow), but numbers were small at depths greater than 30 fathoms.

Spottail shiner (Notropis hudsonius) The trawl tow at 10 fathoms produced the only catch (10 individuals) of spottail shiners. These small numbers may not be indicative of actual abundance, however, since this species pre- fers warmer water than that at the trawling depths. Spottail shiners were seldom found in southeastern Lake Michigan in water colder than 13° C in the warm season.

Trout-perch (Percopsis omiscomaycus) The trawl tow at 10 fathoms off Oswego took 780 trout-perch; only 2 others were taken, both at 15 fathoms in the same area. Trawling in warmer water might have produced more trout-perch since this species in southeastern Lake Michigan preferred water temperatures of 10 to 16° C.

Slimy sculpin (Cottus cognatus) This species was taken in all but the shallowest tows in both trawling areas (Oswego and Rochester). The catches at 30 and 40 fathoms (1,618 and 2,369, respectively) were much larger than any ever made by the Cisco in the other Great Lakes.

Deepwater sculpin (Myoxocephalus quadricornis) This species was not taken, but is mentioned here because its apparent scarcity or absence was in striking contrast to its form- er abundance. Gill nets set by the University of Michigan in Lake Ontario around 1920 took deepwater sculpins at about the same rate as nets fished by the Bureau of Commercial Fisheries in recent years in the Upper Great Lakes (Stanford Smith, personal communication), where deepwater sculpins are considered rather abundant. Dymond et al. (1929) reported them as abundant in the deep Canadian waters of Lake Ontario.

Other species A single lake trout (Salvelinus namaycush), 11.5 inches long, was taken in the gill nets set in 25 fathoms off Rochester; one burbot (Lota lota), length 23.6 inches, was caught in the trawl tow at 15 fathoms off Oswego; a threespine stickleback (Gasteros- teus aculeatus) was in the 30-fathom trawl catch off Rochester; and a yellow perch (Perca flavescens) was taken in the trawl tow at 40 fathoms off Oswego. Johnny darters (Etheostoma nigrum) were caught in small numbers (total, 55) in the tows at 10-20 fathoms off Oswego, and at 15-20 fathoms off Rochester.

Catches in Warm Water

The catches from the gill nets set at 3 fathoms off Olcott were from considerably warmer water than were the other catches (Table 2). Most species taken in this set were not caught elsewhere. The numbers of each species were as follows: alewife, 70; smelt (adult), 19; northern pike (Esox lucius), 1; lake chub (Hybopsis plumbea), 2; white sucker (Catostomus commer- soni), 15; white bass (Morone chrysops), 2; white perch (Morone americanus), 6; rock bass (Ambloplites rupestris), 9; and yellow perch, 5.

Literature Cited

DYMOND, J. R., J. L. HART, and A. L. PRITCHARD. 1929. The fishes of the Canadian waters of Lake Ontario. Univ. Toronto Studies, Biol. Ser. (33), Publ. Ont. Fish. Res. Lab. (37):1-35. PRITCHARD, ANDREW L. 1931. Taxonomic and life history studies of the ciscoes of Lake On- tario. Univ. Toronto Studies, Biol. Ser. (35), Publ. Ont. Fish. Res. Lab. (41):5-78. STONE, UDELL BENNETT. 1947. A study of the deep-water cisco fishery of Lake Ontario with particular reference to the bloater, Leucichythys hoyi (Gill). Trans. Amer. Fish. Soc. (1944), 74:230-249. WELLS, LARUE. 1968. Seasonal depths distribution of fish in southeastern Lake Michi- gan. U.S. Fish Wildl. Serv. Fish. Bull. 67:1-15. APPENDIX Locations of Stations on Lake Ontario

Station Latitude Longitude Latitude Longitude 1 43° 15' 79° 12' 54 43° 36' 77° 24' 2 43 17 79 08 55 43 31 77 27 3 43 19 79 04 56 43 27 77 30 4 43 19 79 06 57 43 22 77 32 5 43 20 79 10 58 43 18 77 34 6 43 22 79 16 59 43 16 77 34 7 43 22 79 20 60 43 20 77 26 8 43 22 79 26 61 43 22 77 20 9 43 21 79 32 62 43 24 77 15 10 43 20 79 38 63 43 26 77 10 11 43 18 79 46 64 43 28 77 04 12 43 22 79 42 65 43 30 76 57 13 43 26 79 38 66 43 30 76 50 14 43 20 79 34 67 43 30 76 44 15 43 34 79 30 68 43 29 76 36 16 43 36 79 26 69 43 29 76 32 17 43 37 79 24 70 43 31 76 34 18 43 34 79 20 71 43 34 76 38 19 43 33 79 10 72 43 32 76 32 20 43 36 79 02 73 43 32 76 26 21 43 41 79 05 74 43 32 76 20 22 43 42 78 59 75 43 36 76 23 23 43 50 78 56 76 43 38 76 23 24 43 46 78 55 77 43 42 76 20 25 43 43 78 55 78 43 46 76 15 26 43 39 78 52 79 43 50 76 20 27 43 35 78 50 80 43 53 76 17 28 43 32 78 48 81 43 56 76 13 29 43 28 78 47 82 43 57 76 10 30 43 24 78 45 83 43 56 76 16 31 43 21 78 44 84 43 56 76 22 32 43 23 78 29 85 43 56 76 26 33 43 26 78 27 86 44 01 76 26 34 43 29 78 23 87 44 04 76 24 35 43 32 78 20 88 44 05 76 30 36 43 37 78 18 89 44 06 76 36 37 43 41 78 16 90 44 10 76 36 38 43 48 78 14 91 44 12 76 40 39 43 52 78 12 92 44 12 76 30 40 43 56 78 10 93 44 10 76 36 41 43 57 78 08 94 44 06 76 40 42 43 56 78 02 95 44 01 76 44 43 43 56 77 56 96 43 56 76 48 44 43 55 77 50 97 43 54 76 52 45 43 55 77 44 98 43 51 76 56 46 43 54 77 38 99 43 50 77 00 47 43 53 77 32 100 43 46 76 56 43 53 77 25 101 43 44 76 53 49 43 53 77 20 102 43 41 76 48 50 43 52 77 16 103 43 38 76 44 51 43 48 77 18 104 43 35 76 40 52 43 44 77 20 105 43 32 76 36 53 43 40 77 22 106 43 29 76 32 GREAT LAKES FISHERY COMMISSION

TECHNICAL REPORT SERIES

No. 1. Use of 3-trifluoromethyl-4-nitrophenol as a selective sea lamprey larvicide, by Vernon C. Applegate, John H. Howell, James W. Moffett, B. G. H. Johnson, and Manning A. Smith. No. 2. Fishery statistical districts of the Great Lakes, by Stanford H. Smith, Howard J. Buettner, and Ralph Hile. No. 3. Commercial fish production in the Great Lakes 1867-1960, by Norman S. Baldwin and Robert W. Saalfeld. No. 4. Estimation of the brook and sea lamprey ammocete populations of three streams, by Bernard R. Smith and Alberton L. McLain. A photoelectric amplifier as a dye detector, by Wesley J. Ebel. No. 5. Collection and analysis of commercial fishery statistics in the Great Lakes, by Ralph Hile. No. 6. Limnological survey of Lake Erie 1959 and 1960, by Alfred M. Beeton. No. 7. The use of alkalinity and conductivity measurements to estimate concentrations of 3-trifluormethyl-4-nitrophenol required for treating lamprey stream, by Richard K. Kanayama. No. 8. Synergism of 5, 2’-dichloro-4’-nitro-salicylanilide and 3-trifluormethyl-4-nitrophenol in a selective lamprey larvicide, by John H. Howell, Everett L. King, Jr., Allen J. Smith, and Lee H. Han- son. No. 9. Detection and measurement of organic lampricide residues, by Stacy L. Daniels, Lloyd L. Kempe, Thomas J. Billy, and Alfred M. Beeton. No. 10. Experimental control of sea lampreys with electricity on the south shore of Lake Superior, 1953-60, by Alberton L. McLain, Bernard R. Smith, and Harry H. Moore. No. 11. The relation between molecular structure and biological activity among mononitrophenols containing halogens, by Vernon C. Apple- gate, B. G. H. Johnson, and Manning A. Smith. Substituted nitrosalicylanilides: A new class of selectively toxic sea lamprey larvicides, by Roland J. Starkey and John H. Howell. No. 12. Physical limnology of Saginaw Bay, Lake Huron, by Alfred M. Beeton, Stanford H. Smith, and Frank H. Hooper. No. 13. Population characteristics and physical conditions of Alewives, Alosa pseudoharengus, in a massive dieoff in Lake Michigan, 1967, by Howard H. Brown, Jr.